A kind of preparation process of metal ceramic powder used for hot sprayingTechnical field
The present invention relates to a kind of preparation processes of metal ceramic powder used for hot spraying, belong to field of thermal spray.
Background technique
The metal ceramic powder of currently employed thermal spraying especially supersonic flame spraying has WC-Ni, WC-Co, WC-CoCr, WC-Cr3C2- Ni, Cr3C2The Metal-ceramie powders powder material such as-NiCr, above-mentioned dusty material can prepare corresponding composite coating,It is widely used in needing the occasion of anticorrosion antiwear in industrial production.Currently, metal ceramic powder mostly uses greatly agglomeration process to makeStandby, technical process is generally made of material mixing and ball milling, mist projection granulating, sintering, broken and sieving classification.
In above-mentioned technique, mist projection granulating is that the metal of fine particle and ceramic particle are agglomerated into larger-size sphericalGrain, convenient for energy smooth powder feeding when spraying.Sintering is and can also to improve spherical shape to remove the organic binder in spheric granulesThe mechanical strength of powder particle does not allow it during spraying powder feeding easily broken.
Inventors have found that the metal ceramic powder that currently employed mist projection granulating obtains all is to be sintered at the same temperatureIt arrives, sintered material obtains the consistent hot spray powder of apparent density using broken, screening and air current classifying.
When being sintered at a lower temperature by the metal ceramic powder of mist projection granulating, the apparent density of powder of acquisition also compared withLow, the powder particle of larger size can sufficiently melt in spraying flame stream or soften the (coating of acquisition relatively cause in this powderIt is close), but small size powder particle is easy to there is a phenomenon where superfusing, and the particle of superfusion is usually adhered to the inner wall of gun barrel, causesStifled rifle and big molten drop phenomenon (even if powder lower limit, which is increased to 20 microns, is not avoided that this big molten drop phenomenon), eventually lead toSpraying process is unstable, and corresponding coating grinding rear surface has pit, and causes its qualification rate also very low.
When being sintered at high temperature by the metal ceramic powder of mist projection granulating, the high (powder of obtained powder particle consistencyLast apparent density is high).In spraying process, the small size compacted particles melted by heating or softening in this powder are abundant but bigThe compacted particles of size be heated in the flame stream of spraying it is insufficient, when particle is struck on matrix, center portion not sufficiently melting orThe part of softening is easy to happen rebound, causes the deposition of powder lower.
When the metal ceramic powder by mist projection granulating is when neutral temperature is sintered, the apparent density of powder of acquisition is also fittedIn, the deposition of powder and and coating consistency it is all moderate.The powder moderate for this apparent density, fine grain powder existStill there is biggish tendency to superfuse in spraying process, therefore, in order to reduce this superfusion phenomenon, need the powder sizeThe lower limit of distribution is improved to 15 microns even 20 microns, so that the utilization rate of mist projection granulating powder be caused to substantially reduce.SeparatelyOutside, to height must also be selected by the metal ceramic powder for spraying this medium apparent density to prepare the coating of high-compactnessSpray parameters (increase spraying when fuel and oxygen consumption), this deposition that will lead to powder again substantially reduces.
As it can be seen that respective coatings are prepared using the consistent metal ceramic powder of apparent density, either low, middle apparent densityOr high apparent density, is all difficult to obtain satisfactory result.Therefore, be badly in need of to the design of traditional metal ceramic powder andPreparation process optimizes, to obtain stable spraying process, the deposition of powder and all higher cermet of coating consistencyPowder.
Summary of the invention
The present invention plans the utilization rate for solving how to improve mist projection granulating metal ceramic powder, keeps the stabilization of spraying processThe problems such as property and the powder spray deposition and coating consistency can not get both.
The technical scheme is that providing a kind of preparation process of metal ceramic powder used for hot spraying, including following stepIt is rapid:
(1) by metal powder and ceramic powders mixing and ball milling, slurry A is obtained；
(2) mist projection granulating is carried out to slurry A, obtains powder B；
(3) powder B is classified, obtain the different powder C of the above granularity of two-stage (respectively powder C1, C2 ...Cn)；
(4) it is sintered varigrained powder C (powder C1, C2 ... Cn) at different temperature respectively, sintering is completedIt is crushed and is classified respectively afterwards, obtain the powder D (respectively powder D1, D2 ... Dn) of different apparent densitys；
(5) the powder D of different apparent densitys is mixed, obtains spraying metal ceramic powder.
Preferably, in powder C, partial size is a microns minimum, and partial size is up to b microns；Wherein 4≤a≤8；50≤b≤60.
Preferably, in step (3), powder B point is n grades, from small to large by granularity, respectively powder C1, C2 ..., Cn,Sintering temperature be respectively T1, T2 ..., Tn, the unit of sintering temperature is DEG C；Wherein, T1 > T2 > ... > Tn, n is bigIn 1 natural number.
Preferably, powder B is divided and obtains the powder of powder C1 of the granularity no more than c micron and granularity greater than c microns for two-stageLast C2, wherein 25≤c≤35.
Preferably, the sintering temperature of powder C1 is 1170-2000 DEG C；The sintering temperature of powder C2 is 1160-1190 DEG C.
Preferably, the sintering temperature of powder C1 is T1 DEG C, and the sintering temperature of powder C2 is T2 DEG C, T2+40 DEG C >=T1 >=T2+10℃。
Preferably, powder B is divided for three-level, respectively powder C1, C2 and C3, granularity is respectively d, e and f microns；ItsIn, d < e < f, a≤d≤a+14 microns；B-14 microns≤f≤b, the size distribution e of powder C2 is between d and f.
Preferably, the sintering temperature of powder C1 is T1 DEG C, and the sintering temperature of powder C2 is T2 DEG C, the sintering temperature of powder C3It is T3 DEG C, T2+30 DEG C >=T1 >=T2+8 DEG C；T3+30℃≥T2≥T3+8℃.Preferably, T2+20 DEG C >=T1 >=T2+10 DEG C；T3+20℃≥T2≥T3+10℃。
Preferably, in powder D, partial size is a microns minimum, and partial size is up to b microns.
Preferably, the metal powder is one of Ni, Co, Cr, Fe, Al and Mo and a variety of；The ceramic powders areWC、Cr3C2、TiC、TiB2, WB and Mo2One of B and a variety of.
Specifically, preparation process of the invention comprises the step of:
(1) by a certain proportion of metal powder (one of Ni, Cr, Co, Fe and Mo or a variety of) and ceramic powders (WC,Cr3C2,TiC,WB,TiB2,Mo2One of B or a variety of) and sintered carbide ball, deionized water, polyvinyl alcohol be put into ball milling10-40 hour of machine ball milling, obtaining cermet mixed slurry, (when the total amount of metal ceramic powder is set to 100 parts, hard is closedThe ratio of gold goal is 700 parts, and the ratio of deionized water is 20-25 parts, and the ratio of polyvinyl alcohol is 2 parts)；
(2) above-mentioned slurry is imported into atomizer tower and carries out mist projection granulating, obtaining shape is that spherical cermet is multipleClose powder；
(3) by the particle after above-mentioned granulation carry out screening and air current classifying acquisition size distribution different two kinds or two kinds withOn spherical metal ceramic powder；(size distribution is divided into two sections: 5-30 microns are 3 with 30-53 microns or size distributionA section 5-20 microns, 20-38 microns and 38-53 microns, or more section)；
(4) it will be sintered in the different powder of above-mentioned size distribution reducing atmosphere furnace and vacuum drying oven at different temperatures,Wherein, particulate powders are sintered at high temperature, obtain the particulate powders of high-compactness (apparent density is high)；The powder of medium sizeEnd is sintered at moderate temperatures, obtains the powder of medium consistency；Coarse grain powder is sintered at a lower temperature obtains low densificationThe coarse grain powder of degree (apparent density is lower)；
(5) powder that above-mentioned sintering obtains is crushed, and again sub-sieve and air current classifying to remove in respective powderThe particle size as caused by crushing process is less than the particle of powder size distribution lower limit.
(6) powder that removal is less than powder size distribution lower limit is subjected to mechanical mixture again and obtains metal-ceramic(particle size distribution of the mixed-powder is 5-53 microns to porcelain powder, also, the lesser apparent density of powder of size is high, sizeBiggish apparent density of powder is lower).
Explanation is further explained to the present invention below, waits the code name of labels expression material in Chinese with P1, P2 ...,It is used merely to facilitate differentiation, the meaning not determined.
Such as selection Ni, Cr, Co, (metal accounts for powder P1 gross mass percentage for one of Fe and Mo or Determination of multiple metal elementsThan the metal powder and WC for 7%-40%), Cr3C2, TiC, WB, TiB2, Mo2One of B or a variety of ceramic powders (ceramicsIt accounts for powder P1 gross mass percentage and obtains mixed-powder P1 for 60%-93%) combination.By P1 respectively with account for P1 gross mass 20-25% deionized water and 2% polyvinyl alcohol ball milling mixing, obtain the slurry P2 that is formed by the uniform mixing and ball milling of said components.It willSlurry P2, which is imported in atomizer tower, carries out spray drying granulation, obtains the metal ceramic powder that granularity is in a certain range distributionThe metal ceramic powder P3 that spray drying obtains is carried out sub-sieve and obtains the different fine grained powder of size distribution with air current classifying by P3Last P4, medium size powder P5 and coarse grain powder P6.
Powder P4, P5 and P6 after classification is respectively charged into graphite boat or ceramic boat, is placed into reducing atmosphereAtmosphere furnace or vacuum drying oven in be sintered.Wherein, particulate powders P4 is sintered at a higher temperature and is crushed, and obtains high causeDensity powder P7 (apparent density of powder is high)；The powder P5 of median particle size is sintered and is crushed under medium sintering temperature,Obtain the powder P8 of medium consistency (apparent density of powder is moderate)；Coarse grain powder P6 is sintered at a lower temperature and is crushed and obtainsObtain the powder P9 of low consistency (apparent density of powder is lower).
P7 is removed using the gentle flow point grade of sub-sieve respectively, what is generated in P8 and P9 powder due to broken is less than respective powderSize is distributed the particle of lower limit, respectively obtains powder P10, P11 and P12.
Powder P10, P11 and P12 after classification is subjected to mechanical mixture, obtains the different mixed Metal-ceramie powder of apparent densityLast P13 (powder particle size is bigger, and apparent density is lower).
In the P13 powder with different apparent densitys obtained by above-mentioned technique, the powder consistency of small size is high, is sendingAlthough quality is small during powder, since its consistency is higher, under the action of powder feeding carrier gas, flame flow center can be admitted to；Also, it is not easy to superfuse in the gun barrel of spray gun since particulate powders consistency is high again, greatly reduces superfusion powder adherencyIn the tendency of gun barrel inner wall.Medium size and large-sized powder particle consistency successively reduce, and on the one hand them can be made in flameIt can be sufficiently heated the state for reaching melting or softening in stream, have when on the other hand can also it be made to strike on matrix preferableSpreading property improves the deposition of powder and the consistency of respective coatings.In this way, size distribution is in not same district in powder P13Between particle its apparent density it is also different, this powder made can basically reach more consistent abundant melting in spraying processOr soft state.This not only substantially avoided the phenomenon that adhering to gun barrel inner wall since fine powder is superfused, and also avoid bulky grainPowder is since the degree that center portion melts and softens not enough powder rebound serious situation occurs, so that the deposition of powderIt is all higher with obtained coating consistency.In addition, being greatly improved by the apparent density of fine powder, occurred in spraying processMolten probability also greatly reduces, so, the size distribution lower limit of the powder can also be reduced to 5 by original 15-20 micronMicron, greatly improves mist projection granulating metal ceramic powder utilization rate obtained also.
The invention has the advantages that improving metal ceramic powder utilization rate, the deposition of thermal spraying is improved, is improvedThe consistency of coating, obtains a preferable resultant effect.
Detailed description of the invention
Fig. 1 shows for a kind of preparation technology flow chart of metal ceramic powder in the prior art；
Fig. 2 is the preparation technology flow chart of one of present invention metal ceramic powder；
Fig. 3 is that WC-12Co powder is sintered at 1195 DEG C, the WC- for obtaining the interface of powder and being prepared by the powder12Co coating cross sections photo；
Fig. 4 is that WC-12Co powder is sintered at 1185 DEG C, the WC- for obtaining the interface of powder and being prepared by the powder12Co coating cross sections photo；
Fig. 5 is that WC-12Co powder is sintered at 1175 DEG C, the WC- for obtaining the interface of powder and being prepared by the powder12Co coating cross sections photo；
Fig. 6 is that WC-12Co powder is being 5-25 microns of high apparent density powder (being sintered at 1195 DEG C) for size distributionWith size distribution be 25~53 microns of low-apparent-density powder (be sintered at 1180 DEG C) mechanical mixture powder section photo andThe WC-12Co coating cross sections photo prepared by the powder.
Specific embodiment
Below with reference to embodiment, the invention will be further described.
Comparative example 1
It (1) is respectively the WC (granularity be~2.5 microns) of 88wt.% and the Co powder (grain of 12wt.% by mass percentDegree is 1-3 microns) it is separately added into ball milling bucket, and powder raw material (WC powder+Co powder, similarly hereinafter) gross mass is accounted for this barrel additionWC-Co hard alloy ball is added by ratio of grinding media to material 6:1 in the deionized water of 23wt.% and the polyvinyl alcohol of 2wt.%, and ball milling 30h is obtainedObtain slurry P1.
(2) slurry P1 is gradually introduced in the tip container of spray drying tower, is spray-dried, to obtain size distributionIn a certain range of spherical shape WC-12Co powder P2.
(3) P2 powder is sintered to the P3 powder for obtaining high-compactness at 1195 DEG C.Sintering furnace used can be band reductionProperty (H2Or NH3Decomposition gas) atmosphere stove, be also possible to vacuum drying oven, keep the temperature 2 hours under the sintering temperature of setting.
(5) the P3 powder that sintering obtains is crushed, the WC-12Co powder of acquisition is respectively P4.
(6) method for using sub-sieve and air current classifying is removed less than 15 microns and micro- greater than 53 in P4 crushed powderThe WC-12Co powder number of the particle of rice, acquisition is P5.
(8) it uses and sprays P5 powder by the supersonic spray gun of fuel of kerosene, under standard parameter (kerosene oil flow:22.6L/h, your flow of oxygen: 56.6m3/ h, powder feeding rate 75g/min, spray distance: 380mm), the WC-12Co coating holes of acquisitionGap rate 1.7% (is tested) with gray level method；The powder painting process is stablized, but gun barrel inner wall abrasion is more serious, and powder deposition is35.2% (corresponding powder and coating cross sections photo are shown in Fig. 3).
Comparative example 2
It (1) is respectively the WC (granularity be~2.5 microns) of 88wt.% and the Co powder (grain of 12wt.% by mass percentDegree is 1-3 micron) be separately added into ball milling bucket, and to this barrel addition account for the deionized water of powder raw material gross mass 23wt.% withWC-Co hard alloy ball is added by ratio of grinding media to material 6:1 in the polyvinyl alcohol of 2wt.%, and ball milling 30h obtains slurry P1.
(2) slurry P1 is gradually introduced in the tip container of spray drying tower, is spray-dried, to obtain size distributionIn a certain range of spherical shape WC-12Co powder P2.
(3) P2 powder is sintered at 1185 DEG C and obtains the moderate P3 powder of consistency.Sintering furnace used can be band alsoOriginality (H2Or NH3Decomposition gas) atmosphere stove, be also possible to vacuum drying oven, keep the temperature 2 hours under the sintering temperature of setting.
(5) the P3 powder that sintering obtains is crushed, the WC-12Co powder of acquisition is respectively P4.
(6) method for using sub-sieve and air current classifying is removed less than 15 microns and micro- greater than 53 in P4 crushed powderThe WC-12Co powder number of the particle of rice, acquisition is P5.
(8) it uses and sprays P5 powder by the supersonic spray gun of fuel of kerosene, under standard parameter (kerosene oil flow:22.6L/h, your flow of oxygen: 56.6m3/ h, powder feeding rate 75g/min, spray distance: 380mm), the WC-12Co coating holes of acquisitionGap rate 0.7% (is tested) with gray level method；The powder painting process is more stable, powder deposition be 40.4% (corresponding powder andCoating cross sections photo is shown in Fig. 4).
Comparative example 3
It (1) is respectively the WC (granularity be~2.5 microns) of 88wt.% and the Co powder (grain of 12wt.% by mass percentDegree is 1-3 micron) be separately added into ball milling bucket, and to this barrel addition account for the deionized water of powder raw material gross mass 23wt.% withWC-Co hard alloy ball is added by ratio of grinding media to material 6:1 in the polyvinyl alcohol of 2wt.%, and ball milling 30h obtains slurry P1.
(2) slurry P1 is gradually introduced in the tip container of spray drying tower, is spray-dried, to obtain size distributionIn a certain range of spherical shape WC-12Co powder P2.
(3) P2 powder is sintered to the P3 powder for obtaining low consistency at 1170 DEG C.Sintering furnace used can be band reductionProperty (H2Or NH3Decomposition gas) atmosphere stove, be also possible to vacuum drying oven, keep the temperature 2 hours under the sintering temperature of setting.
(5) the P3 powder that sintering obtains is crushed, the WC-12Co powder of acquisition is respectively P4.
(6) method for using sub-sieve and air current classifying is removed less than 15 microns and micro- greater than 53 in P4 crushed powderThe WC-12Co powder number of the particle of rice, acquisition is P5.
(8) it uses and sprays P5 powder by the supersonic spray gun of fuel of kerosene, under standard parameter (kerosene oil flow:22.6L/h, your flow of oxygen: 56.6m3/ h, powder feeding rate 75g/min, spray distance: 380mm), the WC-12Co coating holes of acquisitionGap rate 0.3% (is tested) with gray level method；But the powder painting process is unstable, has big molten drop to generate, and coating grinding rear surface hasPoint, dye penetrant inspection is general red serious, and coating is unqualified.
Embodiment 1
It (1) is respectively the WC (granularity be~2.5 microns) of 88wt.% and the Co powder (grain of 12wt.% by mass percentDegree is 1-3 micron) be separately added into ball milling bucket, and to this barrel addition account for the deionized water of powder raw material gross mass 23wt.% withWC-Co hard alloy ball is added by ratio of grinding media to material 6:1 in the polyvinyl alcohol of 2wt.%, and ball milling 30h obtains slurry P1.
(2) slurry P1 is gradually introduced in the tip container of spray drying tower, centrifugal spray drying is carried out, to obtain granularityDifferent spherical WC-12Co powder P2.
(3) it uses screening and P2 powder classification is two kinds of WC- of 5-25 microns He 25-53 microns for granularity by air current classifying12Co powder P3 and P4.
(4) P3 powder is sintered to the P5 powder for obtaining high-compactness at 1195 DEG C, P4 powder is sintered at 1175 DEG CObtain the P6 powder of low consistency.Sintering furnace used can be band reproducibility (H2 or NH3Decomposition gas) atmosphere stove, can alsoTo be vacuum drying oven, 2 hours are kept the temperature under the sintering temperature of setting.
(5) P5 the and P6 powder that sintering obtains is crushed, the WC-12Co powder of acquisition is respectively P7 and P8.
(6) method for using sub-sieve and air current classifying again, removes the particle less than 5 microns in P7 crushed powder,The WC-12Co powder number of acquisition is P9, removes the particle less than 25 microns in P8 crushed powder, the WC-12Co of acquisitionPowder number is P10.
(7) two kinds of powder of P19 and P10 are uniformly mixed using the method for mechanical mixture, obtain that there are its different consistencyMixed WC-12Co powder P11.
(8) it uses and sprays P11 powder by the supersonic spray gun of fuel of kerosene, under standard parameter (kerosene oil flow:22.6L/h, your flow of oxygen: 56.6m3/ h, powder feeding rate 75g/min, spray distance: 380mm) porosity can be obtained it is0.31%；The powder painting process stablizes (the phenomenon that no superfusion powder is adhered to gun barrel inner wall generation, gun barrel inner wall abrasion rateIt is low)；In addition, the deposition of the novel WC-12Co powder is 46.6% (corresponding powder and painting under same spray parametersLayer cross section photo is shown in Fig. 6).
Embodiment 2
It (1) is respectively the WC (granularity be~2.5 microns) of 88wt.% and the Co powder (grain of 12wt.% by mass percentDegree is 1-3 micron) be separately added into ball milling bucket, and to this barrel addition account for the deionized water of powder raw material gross mass 23wt.% withWC-Co hard alloy ball is added by ratio of grinding media to material 6:1 in the polyvinyl alcohol of 2wt.%, and ball milling 30h obtains slurry P1.
(2) slurry P1 is gradually introduced in the tip container of spray drying tower, centrifugal spray drying is carried out, to obtain granularityDifferent spherical WC-12Co powder P2.
(3) using screening and air current classifying by P2 powder classification is 5-20 micron for granularity, and 20-38 microns micro- with 38-53Three kinds of WC-12Co powder P3, P4 and P5 of rice.
(4) P3 powder is sintered to the P6 powder for obtaining high-compactness at 1195 DEG C, P4 powder is sintered at 1185 DEG CObtain the P7 powder of medium consistency.P5 powder is sintered to the P8 powder for obtaining low consistency at 1175 DEG C.Sintering furnace usedIt can be band reproducibility (H2 or NH3Decomposition gas) atmosphere stove, be also possible to vacuum drying oven, kept the temperature under the sintering temperature of setting2 hours.
(5) P6, P7 and the P8 powder for obtaining sintering are broken, and the WC-12Co powder of acquisition is respectively P9, P10 and P11.
(6) method for using sub-sieve and air current classifying again, removes the particle less than 5 microns in P9 crushed powder,The WC-12Co powder number of acquisition is P12, removes the particle less than 20 microns in P10 crushed powder, the WC- of acquisition12Co powder number is P13, removes the particle less than 38 microns in P11 crushed powder, the WC-12Co powder number of acquisitionFor P14.
(7) tri- kinds of powder of P12, P13 and P14 are uniformly mixed using the method for mechanical mixture, obtain that there are its different causeThe WC-12Co powder P15 of density mixing.
(8) it uses and sprays P15 powder by the supersonic spray gun of fuel of kerosene, under standard parameter (kerosene oil flow:22.6L/h, your flow of oxygen: 56.6m3/ h, powder feeding rate 75g/min, spray distance: 380mm) porosity can be obtained it is0.27%；The powder painting process stablizes (the phenomenon that no superfusion powder is adhered to gun barrel inner wall generation, gun barrel inner wall abrasion rateIt is low)；In addition, the deposition of the novel WC-12Co powder is 49.6% under same spray parameters.