Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Detailed Description

The following detailed description of embodiments of the invention is intended to be illustrative, and not to be construed as limiting the invention.

The invention aims to obviously improve the mechanical property and microstructure of the material by adding the rare earth mixed additive, and improve the sintering thermodynamic property by adding the titanium oxide and the yttrium oxide, thereby developing the advanced ceramic matrix composite material suitable for the working environment of an engine.

The granulation powder for molding the rare earth alumina ceramic composite material is prepared from the following raw materials in percentage by weight: 90-92% of rare earth ceramic powder, 6-8% of mixed binder and 1-3% of water. After isostatic pressing, the granulated powder is turned into a required configuration on a lathe and sintered into porcelain under normal pressure.

The specific preparation technical process of the composite material is as follows:

step 1: pretreatment of raw materials:

pretreatment of aluminum oxide: heat treating the alumina powder at 1450 deg.c to make its crystal phase from beta-Al₂O₃All converted to alpha-Al₂O₃Ball-milling the heat-treated alumina powder on a planetary ball mill for not less than 25h to ensure that the granularity of the alumina powder is less than 1000 meshes; wherein, triethanolamine with the concentration of 50 percent is adopted as a grinding agent, and the mass of the grinding agent accounts for 3 to 5 percent of that of the alumina.

Titanium dioxide pretreatment: carrying out heat treatment on titanium dioxide in a corundum crucible to ensure that all anatase titanium dioxide is converted into stable golden red titanium dioxide, and carrying out ball milling on the heat-treated golden red titanium dioxide on a planetary ball mill for not less than 5h to ensure that the granularity of the titanium dioxide is less than 500 meshes. The process of heat treatment of titanium dioxide is as follows:

Yttrium oxide pretreatment: and (3) ball-milling the yttrium oxide on a planetary ball mill for not less than 5h to ensure that the particle size of the yttrium oxide is less than 400 meshes. Yttrium oxide Y₂O₃The method can promote sintering, and the crystal grain boundary exists on the crystal grain boundary of alumina, so that the crystal grain boundary migration rate is reduced, the crystal grain growth is inhibited, and the crystal grain size is uniform to form a compact fiber structure.

Treating the rare earth mixed auxiliary agent: and grinding the rare earth mixing auxiliary agent by adopting a planetary ball mill, wherein the granularity is less than 600 meshes.

The mixed rare earth ion assistant is helpful to improve the microstructure of the alumina ceramic, improve the breaking strength and toughness of the ceramic body, and facilitate the sintering with proper particle size distribution.

La₂O₃The density of the material is improved, and the fracture toughness of the material is obviously improved; sm₂O₃The material sintering is promoted, the heat preservation time is obviously shortened, and the material densification is facilitated; CeO (CeO)₂The volume resistivity of the material is improved, the ceramic fracture path is tortuous, and bridging and branching phenomena occur in cracks, so that the fracture energy is improved, and the mechanical property of the material is improved; pr (Pr) of₂O₃、La₂O₃、Sm₂O₃And Nd₂O₃The dielectric property and piezoelectric property of the material can be greatly improved; la₂O₃、Nd₂O₃And CeO₂The curie point can be effectively moved. The mixed rare earth ion assistant obtained by mixing the five rare earth ions can effectively improve the performance of the alumina ceramic matrix composite.

Preparing a mixed binder: dissolving paraffin and beeswax into 50% PUA reagent (polyester polyurethane acrylic acid) to prepare mixed adhesive, and sealing and storing for later use. The total mass of the paraffin and the beeswax accounts for 8 percent of the total mass of the mixed binder.

Step 2: mixing the alumina, the titanium dioxide, the yttrium oxide, the rare earth mixing auxiliary agent and the silicon carbide fiber treated in the step 1 according to the mixture ratio of 94-96% of the alumina, 0.3-0.5% of the titanium dioxide, 0.35-0.5% of the yttrium oxide, 0.5-1.5% of the silicon carbide fiber and 2.5-3.5% of the rare earth mixing auxiliary agent, performing roll milling and mixing in a ball milling roller for not less than 0.5h, and sieving by a 100-mesh sieve to obtain the rare earth ceramic powder.

And step 3: according to the proportion of 90-92% of rare earth ceramic powder, 6-8% of mixed binder and 1-3% of water, adding the mixed binder and the water into the rare earth ceramic powder to form a prefabricated material, uniformly stirring the prefabricated material, drying and crushing to obtain granulation powder with the granularity of 0.08-0.3 mm; the granulated powder is pseudo-particles, which is beneficial to loading and blank pressing.

And 4, step 4: putting the granulated powder into a die, and carrying out isostatic pressing under the pressure of 150MPa to form a blank with a required shape and structure; the isostatic compaction pressure is uniform, and the powder is endowed with certain blank shape and strength, thereby facilitating subsequent processing. Controlling the rotating speed and the turning amount on a numerical control lathe, and turning the blank into the required size of the component, wherein the purpose of the processing is to endow the blank with certain shape and size precision; and sintering the mixture into porcelain in a silicon-molybdenum rod electric furnace at normal pressure at the temperature of 1640-1660 ℃ to obtain the rare earth ceramic composite material part. The purpose of sintering is to give the material a characteristic microstructure, giving the workpiece a specific strength and characteristic function.

And finally, detecting the breaking strength, hardness, toughness, thermal shock resistance, volume density, electric strength and the like of the material according to GB 5593. The results are shown in table 1, which shows that the breaking strength is improved by more than 2.5 times compared with the currently used 95 alumina ceramic, the fracture toughness is improved by more than 4 times, the mechanical property is obviously improved, the hardness is improved, the thermal shock resistance is improved, the microstructure is improved, the overall performance of the material is improved, and the use reliability, durability and safety of the material are improved. The preparation method adopts the cold isostatic pressing, blank turning and pressureless sintering technology, and has the characteristics of simple process, shorter production period, low cost, convenient manufacture and construction and convenient large-scale production.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.

Claims

1. A rare earth alumina ceramic composite material is characterized in that: the material is prepared from the following raw materials in percentage by weight:

90-92% of rare earth ceramic powder, 6-8% of mixed binder and 1-3% of water;

2. The rare earth alumina ceramic composite of claim 1, wherein: the mixed binder is prepared by dissolving paraffin and beeswax into a PUA reagent.

3. The method for preparing the rare earth alumina ceramic composite material according to claim 2, wherein: the mixed binder is prepared by adding paraffin and beeswax into a PUA reagent with the mass concentration of 50%, wherein the total mass of the paraffin and the beeswax accounts for 8% of the total mass of the mixed binder.

4. A preparation method of a rare earth alumina ceramic composite material is characterized by comprising the following steps: the method comprises the following steps:

step 1: pretreatment of raw materials:

5. The method for preparing the rare earth alumina ceramic composite material according to claim 4, wherein: in the titanium dioxide pretreatment process, the heat treatment process of the titanium dioxide comprises the following steps:

6. The method for preparing the rare earth alumina ceramic composite material according to claim 4, wherein: in step 4, the ceramic is sintered at the temperature of 1640-1660 ℃.

7. The method for preparing the rare earth alumina ceramic composite material according to claim 4, wherein: in the pretreatment process of the alumina, triethanolamine with the concentration of 50 percent is adopted as an abrasive, and the mass of the abrasive accounts for 3 to 5 percent of that of the alumina.

8. The method for preparing the rare earth alumina ceramic composite material according to claim 4, wherein: and 4, after the granulated powder is filled into a die, carrying out isostatic pressing under the pressure of 150MPa to obtain a blank.