Disclosure of Invention
In order to solve the problems mentioned in the background art, the invention provides an ultra-coarse-grain WC-Co hard alloy and a preparation method thereof.
The preparation method of the ultra-coarse grain WC-Co hard alloy comprises the following steps:
Step S1, preparing raw materials comprising, by weight, 4.6-9.2 parts of cobalt powder, 96-102 parts of coarse-grain tungsten carbide powder, 3.6-5.2 parts of functionalized gel, 3.4-4.6 parts of modified permeation promoter, 2.2-2.8 parts of binder and 36-62 parts of organic solvent;
S2, preparing a mixture, namely adding coarse-grain tungsten carbide powder, cobalt powder, functional gel, a modified permeation promoter, a binder and an organic solvent into a rolling ball mill according to parts by weight, ball-milling for 14-20 hours, drying and sieving to obtain the mixture, wherein ball-milling conditions comprise a ball-to-material ratio of 4-6:1, a ball rotating speed of 60-80rpm, drying for 5-7 hours at 80-88 ℃, and sieving meshes of 320-360 meshes;
step S3, granulating, namely sieving the mixture prepared in the step S2, and rolling for 4-6min in a granulator to perform granulating;
step S4, compacting, namely compacting the mixture subjected to the granulating treatment in the step S3 into a green body;
And S5, pressurizing and sintering, namely pressurizing and sintering the green body prepared in the step S4 into the ultra-coarse grain WC-Co hard alloy.
Preferably, in step S4, the pressing pressure is 160-180MPa.
Preferably, in step S5, the pressed green body is sintered under a pressurizing condition, during sintering, the temperature is firstly increased to 370-430 ℃ in a gradient way at a temperature increasing rate of 4-8 ℃ per minute under vacuum, the temperature is kept for 12-18min, then the temperature is increased to 1480-1560 ℃ in a gradient way at a temperature increasing rate of 14-18 ℃ per minute, the temperature is kept for 20-26min under vacuum, then the pressure is increased to 35-45MPa at a temperature increasing rate of 6-8MPa per minute, meanwhile, the temperature is increased to 1770-1830 ℃ in a gradient way at a temperature increasing rate of 20-24 ℃ per minute, the pressure is increased to 84MPa at a pressure increasing rate of 12-16MPa per minute, and the temperature is kept for 2.2-2.6h.
Preferably, the binder is CP60 long-chain chlorinated paraffin.
Preferably, the organic solvent is absolute ethanol.
Preferably, the functionalized gel is prepared by the steps of:
Step A1, adding yttrium oxide into a hydrochloric acid aqueous solution, uniformly stirring, adding tannic acid, heating to 35-45 ℃, stirring and reacting for 3-5 hours, filtering, washing and drying to obtain pretreated yttrium oxide, wherein the mass ratio of the yttrium oxide to the hydrochloric acid aqueous solution to the tannic acid is 2-4:40-60:3-6, and in the process, tannic acid is self-polymerized on the surface of the yttrium oxide to form a poly tannic acid layer on the surface of the yttrium oxide, so that the excellent adhesiveness is given to the yttrium oxide;
Step A2, adding pretreated yttrium oxide, ultrafine tungsten carbide, tantalum carbide and chromium carbide into mixed acid, uniformly stirring, adjusting the pH value to 8-9, stirring for 25-35min, heating to 90-110 ℃, stirring for 2-3h, and cooling to room temperature to obtain modified yttrium oxide, wherein the mass ratio of pretreated yttrium oxide, ultrafine tungsten carbide, tantalum carbide, chromium carbide and mixed acid is 1-3:0.04-0.06:0.01-0.03:0.022-0.034:45-55;
And A3, uniformly mixing the modified yttrium oxide and the cross-linking agent, adding a silicon precursor and absolute ethyl alcohol, stirring until gelation, taking out the gel, washing, and drying to obtain the functional gel, wherein the mass ratio of the modified yttrium oxide to the cross-linking agent to the silicon precursor to the absolute ethyl alcohol is 3-5:2.4-3.2:0.4-0.6:16-22.
Preferably, in the step A1, the mass fraction of the hydrochloric acid aqueous solution is 6-10%.
Preferably, in the step A2, the mixed acid is formed by mixing hydrofluoric acid and concentrated nitric acid according to a mass ratio of 1-2:3.
Preferably, in the step A3, the crosslinking agent is propylene oxide butyl ether, and the silicon precursor is tetraethyl orthosilicate.
Preferably, the modified permeation enhancer is prepared by the following steps:
Step B1, uniformly mixing nano hexagonal boron nitride and alkali liquor, heating to 100-120 ℃, stirring and reacting for 40-50h, centrifuging, washing and drying the precipitate to obtain modified boron nitride, wherein the mass ratio of the nano hexagonal boron nitride to the alkali liquor is 2.2-3.2:500-600;
And B2, ultrasonically dispersing the modified boron nitride in anhydrous DMF, dropwise adding the modified boron nitride into an aluminum dihydrogen phosphate aqueous solution while stirring, controlling the dropwise adding within 15min, adding polyvinyl alcohol after the dropwise adding, heating to 60-70 ℃, and stirring for reacting for 4-6h to obtain the modified permeation enhancer, wherein the mass ratio of the modified boron nitride to the anhydrous DMF (N, N-dimethylformamide), the aluminum dihydrogen phosphate aqueous solution to the polyvinyl alcohol is 3-5:60-70:20-30:0.2-0.6.
Preferably, in the step B1, the alkali liquor is a sodium hydroxide aqueous solution with the mass fraction of 50-60%.
Preferably, the mass fraction of the aluminum dihydrogen phosphate aqueous solution is 35-45%.
Compared with the prior art, the invention has the following beneficial effects:
According to the technical scheme, the poly-tannic acid layer can be adsorbed on the surface of yttrium oxide through hydrogen bond or coordination to form a steric hindrance layer, and can adsorb ultrafine tungsten carbide and tantalum carbide on the surface of pretreated yttrium oxide to serve as synthesis sites of the ultrafine tungsten carbide, tantalum carbide and chromium carbide, and the yttrium oxide has excellent fluidity, so that the poly-tannic acid layer can be filled into pores of WC-Co hard alloy in the sintering process of the WC-Co hard alloy, the compactness is improved, and the wear resistance of the WC-Co hard alloy is improved; the preparation method comprises the steps of forming ultrafine tungsten carbide and tantalum carbide on the surface of pretreated yttrium oxide, wherein the ultrafine tungsten carbide, tantalum carbide and chromium carbide are formed, the ultrafine tungsten carbide can increase the grain boundary area, prevent dislocation movement, improve the hardness of an alloy material, delay crack propagation through crack deflection and bridging, improve the toughness of the alloy material, the presence of tantalum carbide can further improve the toughness of the alloy material by promoting crack bifurcation and grain boundary sliding, refine tungsten carbide grains, cooperatively improve the hardness, toughness, impact resistance and wear resistance, and the presence of chromium carbide can refine tungsten carbide grains to make crack propagation paths more tortuous, improve toughness, and is partially dissolved in cobalt binding phase during sintering, separate chromium elements and concentrate at cobalt/tungsten carbide interfaces or grain boundaries to form high energy barriers, prevent W atoms from diffusing from WC grains to Co phase, and further improve the toughness of WC-Co hard alloy;
According to the technical scheme, the modified yttrium oxide is embedded into a silica gel network structure, so that the fixation of the modified yttrium oxide is realized, the dispersibility of the modified yttrium oxide in the ultra-coarse grain WC-Co hard alloy is further improved, gel is filled into the ultra-coarse grain WC-Co hard alloy system, and a green compact is formed through granulating and pressing, the silica in the silica gel has higher compressive strength, and silicon dioxide in the silica gel reacts with tungsten and cobalt to generate silicide, so that the solubility of tungsten in cobalt can be reduced, the dissolution-precipitation process of tungsten carbide grains is inhibited, the hardness and toughness of the WC-Co hard alloy are improved, meanwhile, si-O-Si bonds between the gel are further reinforced and crosslinked, a more compact silica network structure can be formed in the ultra-coarse grain WC-Co hard alloy system, the ultra-coarse grain WC-Co hard alloy is firmly bonded together through the silica network structure, and the hardness, toughness, impact resistance and wear resistance of the WC-Co hard alloy are further improved;
According to the technical scheme, firstly, nano boron nitride is subjected to hydroxylation modification to obtain modified boron nitride, then the modified boron nitride is uniformly mixed with an aluminum dihydrogen phosphate aqueous solution and polyvinyl alcohol to obtain a modified permeation promoter, the existence of the hydroxyl boron nitride can reduce stress concentration, the size distribution of tungsten carbide crystal grains is more uniform, the grain boundary area is increased, dislocation movement is hindered, the hardness, toughness, impact resistance and wear resistance of the ultra-coarse grain WC-Co hard alloy are improved, in addition, the hydroxyl boron nitride can generate hydrogen bond action with hydroxyl groups on the surface of functionalized gel, the compatibility is improved, meanwhile, the hardness, toughness, impact resistance and wear resistance of the ultra-coarse grain WC-Co hard alloy are further improved, the aluminum dihydrogen phosphate in the aqueous solution can form a reticular structure which is favorable for wrapping modified boron nitride particles, agglomeration of the modified boron nitride particles is prevented, so that the dispersion performance is improved, meanwhile, hydroxyl groups on a polyvinyl alcohol molecular chain can generate condensation reaction with hydroxyl groups on the surface of nano silicon dioxide in the functionalized gel to form stable Si-O-C covalent bonds, so that the polyvinyl alcohol molecules are mutually crosslinked to form a three-dimensional network structure, and the ultra-coarse grain WC-Co hard alloy can be introduced into the ultra-coarse grain WC-Co hard alloy, and the ultra-coarse grain WC-Co hard alloy can have synergistic effect and the ultra-coarse grain WC-Co hard alloy and have the toughness and wear resistance.
Detailed Description
In order that the embodiments of the invention may be more readily understood, the invention will be described in detail with reference to the following examples, which are intended to be illustrative only and are not limiting of the scope of the invention.
The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or equipment used were conventional products available for purchase through regular channels, with no manufacturer noted.
The coarse-grain tungsten carbide powder is produced by Hebei Hua diamond alloy welding material Co., ltd, the CAS number is 12070-13-2, the brand is HZ-WC-2, and the mesh number is 60 mesh; cobalt powder is commercially available from Hebei Yirui alloy welding material Co., ltd, CAS number is Hebei technology, brand is Yirui alloy, technology is atomization method, ultrafine tungsten carbide is produced by Ningbo Luo Fei nanometer technology Co., ltd, CAS number is 12070-12-1, the Fisher average particle size of the product is 100nm, yttria is produced by Hebei Hua Ding alloy welding material Co., ltd, CAS number is 1314-36-9, brand is HZ-Y2O3 -1, tantalum carbide is produced by Hebei silver Bai alloy welding material Co., ltd, CAS number is YB-1, chromium carbide is produced by Qinghai county Tebert metal material Co., ltd, CAS number is TB-1, nano boron nitride is produced by Hebei bimetal Co., ltd, CAS number is 10043-11-5, 30-50nm, polyvinyl alcohol is produced by Hebei Rumex source technology Co., ltd, model is PVA1788, and CP60 long-chain chlorinated paraffin is produced by Hebei environment-friendly technology (Luoyang) Co., ltd.
The present invention will be described in further detail with reference to examples and comparative examples.
Preparation examples 1-3 and comparative preparation examples 1-2 provided a functionalized gel.
Preparation example 1
The preparation example provides a functionalized gel, which is prepared by the following steps:
Step A1, adding yttrium oxide into a hydrochloric acid aqueous solution with the mass fraction of 6%, stirring for 12min to uniformity at the rotating speed of 500rpm, adding tannic acid, heating to 35 ℃, keeping the rotating speed unchanged, continuing stirring for reaction for 3h, filtering, washing with absolute ethyl alcohol and deionized water for 3 times in sequence, and drying at 60 ℃ to constant weight to obtain pretreated yttrium oxide, wherein the mass ratio of the yttrium oxide to the hydrochloric acid aqueous solution to the tannic acid is 2:40:3;
Step A2, adding pretreated yttrium oxide, ultrafine tungsten carbide, tantalum carbide and chromium carbide into mixed acid, stirring for 20min to be uniform at the rotating speed of 600rpm, regulating the pH value to 8 by using 0.2M ammonia water solution, stirring for 25min, heating to 90 ℃, keeping the rotating speed unchanged, continuing stirring for reacting for 2h, and cooling to room temperature to obtain modified yttrium oxide, wherein the mass ratio of the pretreated yttrium oxide to the ultrafine tungsten carbide to the tantalum carbide to the chromium carbide to the mixed acid is 1:0.04:0.01:0.022:45, and the mixed acid is formed by mixing hydrofluoric acid and concentrated nitric acid according to the mass ratio of 1:3;
And A3, stirring the modified yttrium oxide and the epoxypropane butyl ether for 16min at the rotating speed of 700rpm until the mixture is uniform, adding the tetraethoxysilane and the absolute ethyl alcohol, stirring until the mixture is gelled, taking out the gel, washing the gel with deionized water for 3 times, and drying the gel at 60 ℃ until the constant weight is reached, thereby obtaining the functional gel, wherein the mass ratio of the modified yttrium oxide to the epoxypropane butyl ether to the tetraethoxysilane to the absolute ethyl alcohol is 3:2.4:0.4:16.
Preparation example 2
The preparation example provides a functionalized gel, which is prepared by the following steps:
Step A1, adding yttrium oxide into 8% hydrochloric acid aqueous solution by mass fraction, stirring for 16min to uniformity at a rotating speed of 540rpm, adding tannic acid, heating to 40 ℃, stirring for reacting for 4h, filtering, washing with absolute ethyl alcohol and deionized water for 4 times in sequence, and drying to constant weight at 65 ℃ to obtain pretreated yttrium oxide, wherein the mass ratio of the yttrium oxide, the hydrochloric acid aqueous solution and the tannic acid is 3:50:4.5;
Step A2, adding pretreated yttrium oxide, ultrafine tungsten carbide, tantalum carbide and chromium carbide into mixed acid, stirring for 22min to be uniform at the rotating speed of 630rpm, regulating the pH value to 8.5 by using 0.4M ammonia water solution, stirring for 30min, heating to 100 ℃, keeping the rotating speed unchanged, continuing stirring for 2.5h, and cooling to room temperature to obtain modified yttrium oxide, wherein the mass ratio of the pretreated yttrium oxide to the ultrafine tungsten carbide to the tantalum carbide to the chromium carbide to the mixed acid is 2:0.05:0.02:0.028:50, and the mixed acid is formed by mixing hydrofluoric acid and concentrated nitric acid according to the mass ratio of 1.5:3;
And A3, stirring the modified yttrium oxide and the epoxypropane butyl ether for 18min to be uniform at the rotating speed of 720rpm, adding the tetraethoxysilane and the absolute ethyl alcohol, stirring to be gelled, taking out the gel, washing the gel with deionized water for 4 times, and drying the gel at 65 ℃ to be constant weight to obtain the functional gel, wherein the mass ratio of the modified yttrium oxide to the epoxypropane butyl ether to the tetraethoxysilane to the absolute ethyl alcohol is 4:2.8:0.5:19.
Preparation example 3
The preparation example provides a functionalized gel, which is prepared by the following steps:
Step A1, adding yttrium oxide into 10% hydrochloric acid aqueous solution by mass fraction, stirring for 20min to uniformity at the rotating speed of 580rpm, adding tannic acid, heating to 45 ℃, stirring and reacting for 5h, filtering, washing by absolute ethyl alcohol and deionized water for 5 times in sequence, and drying to constant weight at 70 ℃ to obtain pretreated yttrium oxide, wherein the mass ratio of the yttrium oxide, the hydrochloric acid aqueous solution and the tannic acid is 4:60:6;
Step A2, adding pretreated yttrium oxide, ultrafine tungsten carbide, tantalum carbide and chromium carbide into mixed acid, stirring for 24min to be uniform at the rotating speed of 660rpm, regulating the pH value to 9 by using 0.6M ammonia water solution, stirring for 35min, heating to 110 ℃, keeping the rotating speed unchanged, continuing stirring for reacting for 3h, and cooling to room temperature to obtain modified yttrium oxide, wherein the mass ratio of the pretreated yttrium oxide, the ultrafine tungsten carbide, the tantalum carbide and the chromium carbide mixed acid is 3:0.06:0.03:0.034:55, and the mixed acid is formed by mixing hydrofluoric acid and concentrated nitric acid according to the mass ratio of 2:3;
And A3, stirring the modified yttrium oxide and the epoxypropane butyl ether at the rotating speed of 740rpm for 20min to be uniform, adding the tetraethoxysilane and the absolute ethyl alcohol, stirring to gel, taking out the gel, washing the gel with deionized water for 5 times, and drying the gel at 70 ℃ to constant weight to obtain the functional gel, wherein the mass ratio of the modified yttrium oxide to the epoxypropane butyl ether to the tetraethoxysilane to the absolute ethyl alcohol is 5:3.2:0.6:22.
Comparative preparation example 1
The comparative preparation provides a functionalized gel prepared by the steps of:
Step A1, adding yttrium oxide into a hydrochloric acid aqueous solution with the mass fraction of 6%, stirring for 12min to uniformity at the rotating speed of 500rpm, adding malic acid, heating to 35 ℃, keeping the rotating speed unchanged, continuing stirring for reaction for 3h, filtering, washing with absolute ethyl alcohol and deionized water for 3 times in sequence, and drying at 60 ℃ to constant weight to obtain pretreated yttrium oxide, wherein the mass ratio of the yttrium oxide to the hydrochloric acid aqueous solution to the malic acid is 2:40:3;
Step A2, adding pretreated yttrium oxide, ultrafine tungsten carbide, tantalum carbide and chromium carbide into mixed acid, stirring for 20min to be uniform at the rotating speed of 600rpm, regulating the pH value to 8 by using 0.2M ammonia water solution, stirring for 25min, heating to 90 ℃, keeping the rotating speed unchanged, continuing stirring for reacting for 2h, and cooling to room temperature to obtain modified yttrium oxide, wherein the mass ratio of the pretreated yttrium oxide to the ultrafine tungsten carbide to the tantalum carbide to the chromium carbide to the mixed acid is 1:0.04:0.01:0.022:45, and the mixed acid is formed by mixing hydrofluoric acid and concentrated nitric acid according to the mass ratio of 1:3;
And A3, stirring the modified yttrium oxide and the epoxypropane butyl ether for 16min at the rotating speed of 700rpm until the mixture is uniform, adding the tetraethoxysilane and the absolute ethyl alcohol, stirring until the mixture is gelled, taking out the gel, washing the gel with deionized water for 3 times, and drying the gel at 60 ℃ until the constant weight is reached, thereby obtaining the functional gel, wherein the mass ratio of the modified yttrium oxide to the epoxypropane butyl ether to the tetraethoxysilane to the absolute ethyl alcohol is 3:2.4:0.4:16.
Comparative preparation example 2
The comparative preparation provides a functionalized gel prepared by the steps of:
Step A1, adding yttrium oxide into a hydrochloric acid aqueous solution with the mass fraction of 6%, stirring for 12min to uniformity at the rotating speed of 500rpm, adding tannic acid, heating to 35 ℃, keeping the rotating speed unchanged, continuing stirring for reaction for 3h, filtering, washing with absolute ethyl alcohol and deionized water for 3 times in sequence, and drying at 60 ℃ to constant weight to obtain pretreated yttrium oxide, wherein the mass ratio of the yttrium oxide to the hydrochloric acid aqueous solution to the tannic acid is 2:40:3;
Step A2, adding pretreated yttrium oxide, ultrafine tungsten carbide, tantalum carbide and chromium carbide into mixed acid, stirring for 20min to be uniform at the rotating speed of 600rpm, regulating the pH value to 8 by using 0.2M ammonia water solution, stirring for 25min, heating to 90 ℃, keeping the rotating speed unchanged, continuing stirring for reacting for 2h, and cooling to room temperature to obtain modified yttrium oxide, wherein the mass ratio of the pretreated yttrium oxide to the ultrafine tungsten carbide to the tantalum carbide to the chromium carbide to the mixed acid is 1:0.04:0.01:0.022:45, and the mixed acid is formed by mixing hydrofluoric acid and concentrated nitric acid according to the mass ratio of 1:3;
And A3, stirring the modified yttrium oxide and the epoxypropane butyl ether for 16min at the rotating speed of 700rpm until the mixture is uniform, adding nano silicon dioxide and absolute ethyl alcohol, stirring until the mixture is gelled, taking out the gel, washing the gel with deionized water for 3 times, and drying the gel at 60 ℃ until the constant weight is reached to obtain the functionalized gel, wherein the mass ratio of the modified yttrium oxide to the epoxypropane butyl ether to the nano silicon dioxide to the absolute ethyl alcohol is 3:2.4:0.4:16.
Preparation examples 4-6 and comparative preparation examples 3-5 provide a modified permeation enhancer.
Preparation example 4
The preparation example provides a modified permeation enhancer, which is prepared by the following steps:
step B1, stirring nano hexagonal boron nitride and 50% sodium hydroxide aqueous solution by mass fraction for 14min to uniformity at the rotating speed of 600rpm, heating to 100 ℃, maintaining the rotating speed unchanged, continuing stirring and reacting for 40h, centrifuging, washing the precipitate with absolute ethyl alcohol for 3 times, and drying at 60 ℃ to constant weight to obtain modified boron nitride, wherein the mass ratio of the nano hexagonal boron nitride to the 50% sodium hydroxide aqueous solution by mass fraction is 2.2:500;
And B2, ultrasonically dispersing the modified boron nitride in anhydrous DMF, controlling the ultrasonic frequency to be 40kHz, the ultrasonic power to be 600w, performing ultrasonic treatment for 16min, controlling the rotating speed to be 660rpm, dropwise adding the modified boron nitride into an aluminum dihydrogen phosphate aqueous solution with the mass fraction of 35% while stirring, controlling the dropwise adding time to be 15min, adding polyvinyl alcohol after the dropwise adding, heating to 60 ℃, keeping the rotating speed unchanged, and continuously stirring and reacting for 4h to obtain the modified permeation enhancer, wherein the mass ratio of the modified boron nitride, the anhydrous DMF, the aluminum dihydrogen phosphate aqueous solution and the polyvinyl alcohol is 3:60:20:0.2.
Preparation example 5
The preparation example provides a modified permeation enhancer, which is prepared by the following steps:
Step B1, stirring nano hexagonal boron nitride and 55% sodium hydroxide aqueous solution at a rotating speed of 640rpm for 18min to be uniform, heating to 110 ℃, keeping the rotating speed unchanged, continuing stirring and reacting for 45h, centrifuging, washing the precipitate with absolute ethyl alcohol for 4 times, and drying the precipitate to constant weight at 65 ℃ to obtain modified boron nitride, wherein the mass ratio of the nano hexagonal boron nitride to the 55% sodium hydroxide aqueous solution is 2.7:550;
And B2, ultrasonically dispersing the modified boron nitride in anhydrous DMF, controlling the ultrasonic frequency to be 35kHz, the ultrasonic power to be 550w, ultrasonically treating for 20min, controlling the rotating speed to be 680rpm, dropwise adding the modified boron nitride into an aluminum dihydrogen phosphate aqueous solution with the mass fraction of 40% while stirring, controlling the dropwise adding time to be 15min, adding polyvinyl alcohol after dropwise adding, heating to 65 ℃, keeping the rotating speed unchanged, and continuously stirring and reacting for 5h to obtain the modified permeation enhancer, wherein the mass ratio of the modified boron nitride, the anhydrous DMF, the aluminum dihydrogen phosphate aqueous solution and the polyvinyl alcohol is 4:65:25:0.4.
Preparation example 6
The preparation example provides a modified permeation enhancer, which is prepared by the following steps:
Step B1, stirring nano hexagonal boron nitride and 60% sodium hydroxide aqueous solution at 680rpm for 22min to be uniform, heating to 120 ℃, stirring for reaction for 50h, centrifuging, washing the precipitate with absolute ethyl alcohol for 5 times, and drying to constant weight at 70 ℃ to obtain modified boron nitride, wherein the mass ratio of the nano hexagonal boron nitride to the 60% sodium hydroxide aqueous solution is 3.2:600;
And B2, ultrasonically dispersing the modified boron nitride in anhydrous DMF, controlling the ultrasonic frequency to be 30kHz, the ultrasonic power to be 500w, ultrasonically treating for 24min, controlling the rotating speed to be 700rpm, dropwise adding the modified boron nitride into an aluminum dihydrogen phosphate aqueous solution with the mass fraction of 45% while stirring, controlling the dropwise adding time to be 15min, adding polyvinyl alcohol after dropwise adding, heating to 70 ℃, keeping the rotating speed unchanged, and continuously stirring and reacting for 6h to obtain the modified permeation enhancer, wherein the mass ratio of the modified boron nitride, the anhydrous DMF, the aluminum dihydrogen phosphate aqueous solution and the polyvinyl alcohol is 5:70:30:0.6.
Comparative preparation example 3
The comparative preparation provides a modified permeation enhancer which is prepared by the following steps:
Step B1, stirring nano hexagonal boron nitride and deionized water for 14min at the rotating speed of 600rpm until the nano hexagonal boron nitride and the deionized water are uniform, heating to 100 ℃, maintaining the rotating speed unchanged, continuing stirring reaction for 40h, centrifuging, washing the precipitate with absolute ethyl alcohol for 3 times, and drying at 60 ℃ until the weight is constant to obtain modified boron nitride, wherein the mass ratio of the nano hexagonal boron nitride to the deionized water is 2.2:500;
And B2, ultrasonically dispersing the modified boron nitride in anhydrous DMF, controlling the ultrasonic frequency to be 40kHz, the ultrasonic power to be 600w, performing ultrasonic treatment for 16min, controlling the rotating speed to be 660rpm, dropwise adding the modified boron nitride into an aluminum dihydrogen phosphate aqueous solution with the mass fraction of 35% while stirring, controlling the dropwise adding time to be 15min, adding polyvinyl alcohol after the dropwise adding, heating to 60 ℃, keeping the rotating speed unchanged, and continuously stirring and reacting for 4h to obtain the modified permeation enhancer, wherein the mass ratio of the modified boron nitride, the anhydrous DMF, the aluminum dihydrogen phosphate aqueous solution and the polyvinyl alcohol is 3:60:20:0.2.
Comparative preparation example 4
The comparative preparation provides a modified permeation enhancer which is prepared by the following steps:
step B1, stirring nano hexagonal boron nitride and 50% sodium hydroxide aqueous solution by mass fraction for 14min to uniformity at the rotating speed of 600rpm, heating to 100 ℃, maintaining the rotating speed unchanged, continuing stirring and reacting for 40h, centrifuging, washing the precipitate with absolute ethyl alcohol for 3 times, and drying at 60 ℃ to constant weight to obtain modified boron nitride, wherein the mass ratio of the nano hexagonal boron nitride to the 50% sodium hydroxide aqueous solution by mass fraction is 2.2:500;
and B2, ultrasonically dispersing the modified boron nitride in anhydrous DMF, controlling the ultrasonic frequency to be 40kHz, the ultrasonic power to be 600w, performing ultrasonic treatment for 16min, controlling the rotating speed to be 660rpm, dropwise adding the modified boron nitride into an aluminum dihydrogen phosphate aqueous solution with the mass fraction of 35% while stirring, controlling the dropwise adding time to be 15min, adding absolute ethyl alcohol after dropwise adding, heating to 60 ℃, keeping the rotating speed unchanged, and continuously stirring for reacting for 4h to obtain the modified permeation enhancer, wherein the mass ratio of the modified boron nitride, the anhydrous DMF, the aluminum dihydrogen phosphate aqueous solution and the absolute ethyl alcohol is 3:60:20:0.2.
Comparative preparation example 5
The comparative preparation provides a modified permeation enhancer which is prepared by the following steps:
step B1, stirring nano hexagonal boron nitride and 50% sodium hydroxide aqueous solution by mass fraction for 14min to uniformity at the rotating speed of 600rpm, heating to 100 ℃, maintaining the rotating speed unchanged, continuing stirring and reacting for 40h, centrifuging, washing the precipitate with absolute ethyl alcohol for 3 times, and drying at 60 ℃ to constant weight to obtain modified boron nitride, wherein the mass ratio of the nano hexagonal boron nitride to the 50% sodium hydroxide aqueous solution by mass fraction is 2.2:500;
And B2, ultrasonically dispersing the modified boron nitride in anhydrous DMF, controlling the ultrasonic frequency to be 40kHz, the ultrasonic power to be 600w, performing ultrasonic treatment for 16min, controlling the rotating speed to be 660rpm, dropwise adding the modified boron nitride into a disodium hydrogen phosphate aqueous solution with the mass fraction of 35% while stirring, controlling the dropwise adding time to be 15min, adding polyvinyl alcohol after the dropwise adding, heating to 60 ℃, keeping the rotating speed unchanged, and continuously stirring and reacting for 4h to obtain the modified permeation enhancer, wherein the mass ratio of the modified boron nitride, the anhydrous DMF, the disodium hydrogen phosphate aqueous solution and the polyvinyl alcohol is 3:60:20:0.2.
Examples 1-3 and comparative examples 1-5 provide a method for preparing ultra-coarse grain WC-Co cemented carbide.
Example 1
The embodiment provides a preparation method of ultra-coarse grain WC-Co hard alloy, which comprises the following steps:
Step S1, preparing the following raw materials, by weight, 4.6 parts of cobalt powder, 96 parts of coarse-grain tungsten carbide powder, 3.6 parts of functionalized gel prepared in preparation example 1, 3.4 parts of modified permeation enhancer prepared in preparation example 4, 2.2 parts of CP60 long-chain chlorinated paraffin and 36 parts of absolute ethyl alcohol;
S2, preparing a mixture, namely adding coarse-grain tungsten carbide powder, cobalt powder, functional gel, a modified permeation promoter, CP60 long-chain chlorinated paraffin and absolute ethyl alcohol into a rolling ball mill according to parts by weight, controlling the ball material ratio to be 4:1, controlling the ball rotation speed to be 60rpm, performing ball milling for 14 hours, drying at 80 ℃ for 5 hours, and sieving with a 320-mesh sieve to obtain the mixture, wherein the ball material ratio of hard alloy, grinding balls and solid raw materials is 1:1:1;
Step S3, granulating, namely sieving the mixture prepared in the step S2 with a 80-mesh sieve, and rolling in a granulator for 4min to perform granulating;
step S4, compacting, namely compacting the mixture subjected to the granulating treatment in the step S3 into a green body under 160 MPa;
And S5, pressurizing and sintering, namely pressurizing and sintering the green body prepared in the step S4 into the ultra-coarse grain WC-Co hard alloy, wherein during sintering, the temperature is firstly increased to 370 ℃ in a gradient manner under vacuum, the temperature is kept for 12min, then the temperature is increased to 1480 ℃ in a gradient manner under 14 ℃ in the heating rate of 14 ℃ per min, the temperature is kept for 20min in the vacuum, the pressure is increased to 35MPa in the heating rate of 6MPa per min, the temperature is increased to 1770 ℃ in the heating rate of 20 ℃ per min, the pressure is increased to 84MPa in the pressurizing rate of 12MPa per min, and the temperature is kept for 2.2h.
Example 2
The embodiment provides a preparation method of ultra-coarse grain WC-Co hard alloy, which comprises the following steps:
Step S1, preparing the following raw materials, by weight, 6.9 parts of cobalt powder, 99 parts of coarse-grain tungsten carbide powder, 4.4 parts of functionalized gel prepared in preparation example 2, 4.0 parts of modified permeation enhancer prepared in preparation example 5, 2.5 parts of CP60 long-chain chlorinated paraffin and 49 parts of absolute ethyl alcohol;
S2, preparing a mixture, namely adding coarse-grain tungsten carbide powder, cobalt powder, functional gel, a modified permeation promoter, CP60 long-chain chlorinated paraffin and absolute ethyl alcohol into a rolling ball mill according to parts by weight, controlling the ball material ratio to be 5:1, controlling the ball rotation speed to be 70rpm, performing ball milling for 17 hours, placing the mixture at 84 ℃, drying for 6 hours, and sieving the mixture through a 340-mesh sieve to obtain the mixture, wherein the ball material ratio of hard alloy, grinding balls and solid raw materials is 1:2:1;
Step S3, granulating, namely sieving the mixture prepared in the step S2 with a 100-mesh sieve, and rolling in a granulator for 5min to perform granulating;
Step S4, compacting, namely compacting the mixture subjected to the granulating treatment in the step S3 into a green body under 170 MPa;
And S5, pressurizing and sintering, namely pressurizing and sintering the green body prepared in the step S4 into the ultra-coarse grain WC-Co hard alloy, wherein during sintering, the temperature is firstly increased to 400 ℃ in a gradient way under vacuum at the heating rate of 6 ℃ per minute, the temperature is kept for 15 minutes, then the temperature is increased to 1520 ℃ in a gradient way under the heating rate of 16 ℃ per minute, the temperature is kept for 23 minutes under vacuum, then the pressure is increased to 40MPa at the heating rate of 7MPa per minute, and meanwhile, the temperature is increased to 1800 ℃ in a gradient way at the heating rate of 22 ℃ per minute, and then the pressure is increased to 84MPa at the pressurizing rate of 14MPa per minute, and the temperature is kept for 2.4 hours.
Example 3
The embodiment provides a preparation method of ultra-coarse grain WC-Co hard alloy, which comprises the following steps:
Step S1, preparing the following raw materials, by weight, 9.2 parts of cobalt powder, 102 parts of coarse-grain tungsten carbide powder, 5.2 parts of functionalized gel prepared in preparation example 3, 4.6 parts of modified permeation enhancer prepared in preparation example 6, 2.8 parts of CP60 long-chain chlorinated paraffin and 62 parts of absolute ethyl alcohol;
S2, preparing a mixture, namely adding coarse-grain tungsten carbide powder, cobalt powder, functional gel, a modified permeation promoter, CP60 long-chain chlorinated paraffin and absolute ethyl alcohol into a rolling ball mill according to parts by weight, controlling the ball material ratio to be 6:1, controlling the ball rotation speed to be 80rpm, performing ball milling for 20 hours, placing at 88 ℃ and drying for 7 hours, and sieving through a 360-mesh sieve to obtain the mixture, wherein the ball material ratio of hard alloy, grinding balls and solid raw materials is 1:3:1;
step S3, granulating, namely sieving the mixture prepared in the step S2 with a 120-mesh sieve, and rolling in a granulator for 6min to perform granulating;
Step S4, compacting, namely compacting the mixture subjected to the granulating treatment in the step S3 into a green body under 180 MPa;
And S5, pressurizing and sintering, namely pressurizing and sintering the green body prepared in the step S4 into the ultra-coarse grain WC-Co hard alloy, wherein during sintering, the temperature is firstly increased to 430 ℃ in a gradient manner under vacuum, the temperature is kept for 18min, then the temperature is increased to 1560 ℃ in a gradient manner under 18 ℃ in the heating rate of 18 ℃ in the vacuum, the temperature is kept for 26min in the vacuum, the pressure is increased to 45MPa in the heating rate of 8MPa in the vacuum, the temperature is increased to 1830 ℃ in the heating rate of 24 ℃ in the gradient manner, and the pressure is increased to 84MPa in the pressurizing rate of 16MPa in the vacuum, and the temperature is kept for 2.6h.
Comparative example 1
Comparative example 1 the same as example 1 was only different in that the functionalized gel in example 1 was replaced with the functionalized gel prepared in comparative preparation 1.
Comparative example 2
Comparative example 2 differs from example 1 only in that the functionalized gel in example 1 was replaced with the functionalized gel prepared in comparative preparation 2.
Comparative example 3
Comparative example 3 the same as example 1 was carried out except that the modified permeation enhancer in example 1 was replaced with the modified permeation enhancer prepared in comparative preparation example 3.
Comparative example 4
Comparative example 4 the same as example 1 was carried out except that the modified permeation enhancer in example 1 was replaced with the modified permeation enhancer prepared in comparative preparation example 4.
Comparative example 5
Comparative example 5 the same as example 1 was carried out except that the modified permeation enhancer in example 1 was replaced with the modified permeation enhancer prepared in comparative preparation example 5.
Performance testing
The ultra-coarse grain WC-Co cemented carbides prepared in examples 1-3 and comparative examples 1-5 were subjected to the following performance tests:
Preparing test samples, namely cutting and grinding the ultra-coarse-grain WC-Co hard alloy prepared in the examples 1-3 and the comparative examples 1-5 into test samples with the size of 5.25mm multiplied by 6.5mm multiplied by 20 mm;
flexural strength, namely testing according to GB/T232-2024, and testing the flexural strength of each test sample by adopting a three-point bending method;
Vickers hardness room temperature Hardness (HV) of each test piece was measured on a vickers hardness tester under a load of 30kg, and fracture toughness (KIC) was calculated from the radial crack length generated by vickers hardness indentation according to the Nihara formula in mpa.m1/2;
wear resistance test the hard alloy wires prepared in examples 1-3 and comparative examples 1-5 were cut and ground to prepare test bars with a size of 8mm x 12mm x 20mm, and the wear rate of each test bar was measured by a wear tester, the test load was 50N, the friction ring rotation speed was 200rpm, the time was 2 hours, and the wear rate was calculated as:
Impact resistance the ultra-coarse-grained WC-Co cemented carbides prepared in examples 1-3 and comparative examples 1-5 were cut and ground into test bars having dimensions of 5mm by 50mm, respectively, and the impact strength of each test bar was measured by a pendulum impact tester with reference to GB/T1817-2017, and the specific test results are shown in Table 1:
TABLE 1 Performance test results
From the data in Table 1, it is understood that the ultra-coarse-grain WC-Co cemented carbides prepared in examples 1 to 3 have more excellent hardness, toughness, impact resistance and wear resistance than those of comparative examples 1 to 5.
According to the performance data of the example 1 and the comparative example 1, the presence of tannic acid can form a poly tannic acid layer on the surface of yttrium oxide, the poly tannic acid layer can be adsorbed on the surface of yttrium oxide through hydrogen bond or coordination, a steric hindrance layer is formed, activated carbon generated by decomposition of the poly tannic acid can participate in Co/WC interface reaction to form more stable chemical bonding, and the toughness, impact resistance and wear resistance of the ultra-coarse crystal WC-Co hard alloy are remarkably improved.
According to the test results of the embodiment 1 and the comparative example 2, the silica gel has higher compressive strength, and silicon dioxide in the silica gel reacts with tungsten and cobalt to generate silicide, so that the dissolution-precipitation process of tungsten carbide grains is inhibited, the hardness and toughness of WC-Co hard alloy are improved, meanwhile, si-O-Si bonds between the gels are further reinforced and crosslinked, a more compact silicon dioxide network structure can be formed in an ultra-coarse-grain WC-Co hard alloy system, and the hardness, toughness, impact resistance and wear resistance of the ultra-coarse-grain WC-Co hard alloy are remarkably improved.
According to the comparative analysis of example 1 and comparative example 3, compared with nano boron nitride, the hydroxyl boron nitride can generate hydrogen bond action with hydroxyl on the surface of the functionalized gel, so that the compatibility is improved, and meanwhile, the hardness, toughness, impact resistance and wear resistance of the ultra-coarse-grain WC-Co hard alloy are remarkably improved.
According to the test results of the embodiment 1 and the comparative example 4, the hydroxyl groups on the molecular chain of the polyvinyl alcohol can be subjected to condensation reaction with the hydroxyl groups on the surface of the nano silicon dioxide in the functionalized gel to form stable Si-O-C covalent bonds, so that the polyvinyl alcohol molecules are mutually crosslinked to form a three-dimensional network structure, and the hardness, toughness, impact resistance and wear resistance of the ultra-coarse-grain WC-Co hard alloy are remarkably improved.
According to the test results of the embodiment 1 and the comparative example 5, aluminum dihydrogen phosphate can form a net structure in an aqueous solution, which is helpful for wrapping modified boron nitride particles, preventing agglomeration, thereby improving the dispersion performance and remarkably improving the hardness, toughness, impact resistance and wear resistance of the ultra-coarse-grain WC-Co hard alloy.
The present embodiment is only for explanation of the present invention and is not to be construed as limiting the present invention, and modifications to the present embodiment, which may not creatively contribute to the present invention as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present invention.