Research Of Preparation And Structure Properties Of Mo₂NiB₂ Based Cermet

Mo₂NiB₂-based cermet have good properties of corrosion resistance,abrasive resistance and high-temperature oxidation resistance.The current research of this materials is less,therefore the further system research of materials preparation,elements' effect and grain refinement are needed.This paper has mainly researched that based on raw material of NiB?Mo?Cr?Ni and V,preparing Mo₂NiB₂-based cermet by vacuum liquid phase sintering.The effect of sintering process,alloy elements,grain inhibitor on microstructure,mechanical properties and corrosion resistance of Mo₂NiB₂-based cermet has been researched.The research of preparation and sintering process of Mo₂NiB₂-based cermet showed that: the optimal sintering process: taking 480?,800?,900?,1100?,1200? as insulation points and 1330? as ultimate temperature.The effect of Mo/B atom ratio,Cr,V alloy elements on microstructure and properties of Mo₂NiB₂-based cermet,the results revealed that: the optimal atom ratio Mo/B was 1:1,Mo₂NiB₂-based cermet had optimal two phase composition,and its microstructure and properties were optimal.Through scanning analysis,Cr and V elements existed in both hard phase and binder phase,and V element mainly existed in hard phase.Cr and V elements can improve hardness and bending strength of Mo₂NiB₂-based cermet.And V element can influence hardness obviousl y.Cr element can promote hard phase of Mo₂NiB₂-based cermet from prismatic crystal to tetragonal crystal,and V element can promote the transformation process.To further increase properties of materials and refine grain.The effect of grain inhibitor on grain refining of Mo₂NiB₂-based cermet,the result showed that: Cr₃C₂ and Sm₂O₃ which consider as grain inhibitor can refine grain of Mo₂NiB₂-based cermet,however they had no influent on basic composition of materials.Adding Cr₃C₂ and Sm₂O₃ alone,the optimum amount of Cr₃C₂ was 0.8% and Sm₂O₃ was 0.6%.Comparing the two inhibitor,the influence of Sm₂O₃ was better than that of Cr₃C₂,the size of grain up to 1.2?m with adding 0.6%Sm₂O₃.And Mo₂NiB₂-based cermet which contained Sm₂O₃ was dense and it had no void.At last,in the research of corrosion resistance,Cr element can effectively improve corrosion resistance of Mo₂NiB₂-based cermet.And the corrosion resistance of Mo₂NiB₂-based cermet which contained Cr element was better than that of Mo2 Fe B2-based cermet and YG8,and it can equal with 304 stainless steel in 10%HNO3-3%HF solution.However its corrosion resistance was worse than that of YG8 when the test solution was 5% Na Cl.