Gel injection molding of water-soluble epoxy resin with zirconia ceramics

The molding method of zirconia ceramics determines its ceramic strength and density, and indirectly determines the hardness and wear resistance of ceramic parts. Below, Kezhong Ceramics Factory will introduce the gel injection molding of zirconia ceramics with water-soluble epoxy resin.

In the early 1990s, Professor JANNY and Professor OMATETE of Oak Ridge State Key Laboratory in the United States invented the gel-casting technology of ceramic materials [1− 3], as a unique and promising new ceramic molding process, this technology has attracted wide attention, and can obtain green materials with uniform structure, high density, high strength and net size. Gel injection molding usually adopts two gel systems: non-water-based gel system and water-based gel system. For the sake of green and environmental protection, non-water-based gel system has been gradually replaced by water-based gel system.

The commonly used water-based gel systems are acrylate system and acrylamide system, but the solubility of acrylate monomer in water is low and acrylamide gel system is toxic, so these two systems can not meet the needs of industrial application.

Zirconia ceramics have excellent properties such as high strength, high hardness, high elastic modulus and good chemical stability, and have wide application prospects in catalysts, high-temperature solid fuel cells, refractories and biomaterials. Acrylamide gel system is mostly used in the research of ZrO _ 2 gel injection molding, but acrylamide gel system is toxic, and the dispersion of ZrO _ 2 ceramic powder is poor, so it is difficult to form a slurry with good fluidity.

In recent years, some people use gel formed by natural macromolecules in physical or chemical changes to carry out ceramic gel injection molding. For example, ADOLFSSON et al. [4] prepared ZrO2 ceramics with agarose, CHEN et al. [5] prepared alumina ceramics with strength of 8 MPa with gelatin, BENGISU et al. [6] injected zirconia and alumina ceramics with chitosan, and ERIK[7] injected zirconia ceramics with nontoxic agar gel.

The strength of the green bodies obtained by the above methods is not high. GREGOROVA et al. [8] used vegetable gum to form ZrO2 ceramics, and the volume fraction of solid phase was less than 30%. Dong Manjiang et al [9− [13] Water-soluble epoxy resin was applied to gel casting of ZrO _ 2 and SiC, and the solid volume fraction of ZrO _ 2 slurry was as high as 53.7%. As a kind of water-soluble epoxy resin, hydantoin epoxy resin has the advantages of low toxicity, low cost, good water solubility and high strength, and has a good application prospect in gel injection molding of structural ceramics.

XIE et al. [14] used hydantoin epoxy resin system to obtain alumina ceramic green body with strength as high as 43.4 MPa, and Zhao Yang et al. [15] used the same system to prepare piezoelectric ceramic transducer with strength as high as 77.8 MPa. However, there are few studies on the preparation of zirconia ceramics by using hydantoin epoxy resin. Therefore, in this paper, low molecular weight ammonium polyacrylate (NH4PAA) was selected as dispersant, water-soluble hydantoin epoxy resin was used as gelling agent, and 3,3-diaminodipropylamine (DPTA) was used as curing agent. Zirconia ceramics were prepared by gel casting and pressureless sintering of ZrO2－-hydantoin epoxy resin system, and the effects of dispersant content and solid content on the rheological properties of slurry and the properties of green and sintered samples were studied.

conclusion

1) When the mass fraction of dispersant is 0.8%, the mass fraction of epoxy resin is 8%, and the volume fraction of solid phase is 50%, the viscosity of the slurry is 0.46 Pa/s (shear rate is 100 s− 1) Low viscosity ZrO2 ceramic slurry suitable for casting.

2) The particles in the zirconia ceramic green body formed by coagulation injection molding are closely combined, uniform in structure and good in compactness, and the strength of the green body reaches 61.05 MPa, which fully meets the strength requirements of mechanical processing.

3) The green zirconia ceramics formed by gel injection molding were sintered at 1500℃, and the bending strength of the zirconia ceramics was 672.52 MPa, and the relative density was 98.26%, mainly t-ZrO2.

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