Preparation And Properties Research Of Al₂O₃ Particle Reinforced Molybdenum Composites

Molybdenum alloys have a wide range of applications at high temperature anti-wear areas, such as head of perforated stainless steel tube, rocket launchers of the nozzle and spout, extrusion molds of non-ferrous metals and die casting molds of steels, boat and plate of rare earth sintered magnet, and so on. Currently used Molybdenum alloys have very little hard phase, so their high-temperature anti-wear capacity was limited, and it's difficult to meet the requirements. To develop the field in anti-wear applications at high temperature areas, so search for molybdenum alloy or composite materials with high-temperature anti-wear properties have a very important significance.In this paper mixed molybdenum powder were prepared by solid-solid, liquid-solid and sol-gel incorporation method; the particle reinforced molybdenum-based composites were prepared by PM process as Al₂O₃ volume fraction was 3%, 5%, 7%, 10%. The morphology of the mixed molybdenum powder, microstructure of composite materials and morphology of wear were observed by SEM; mixed molybdenum powder and phase structure of composite materials were analysised by XRD; The particle size of mixed molybdenum powder, microhardness of matrix, the density of composite materials, the friction coefficient and wear were measured. The results show that, the mixed molybdenum powder made by the Mo andα-Al₂O₃; Al₂O₃ refined and uniformed the particle size of mixed molybdenum powder inthe hydrogen reduction process. Mixed molybdenum powder with MoO2 as raw materials and sol-gel prepared were approximately spherical, and with MoO3 as the raw material mixed molybdenum powder obtained non-uniform particle size, and has a multilateral shape, which have more cluster-like aggregates; The mixed molybdenum powder have a better pressing performance,when with MoO₂ as raw materials than with MoO₃.The composite materials prepared by the Mo andα-Al₂O₃; with the volume fraction of Al₂O₃ increased, the density of composites first increased and then decreased, micro-hardness of the molybdenum matrix are increasing. Al₂O₃ particles uniform and small when composite materials prepared by liquid-solid methods, and Al₂O₃ particles are larger and irregular morphology as other methods.With the Al₂O₃ content changes the impact on the friction coefficient is not obvious, the friction coefficient value fluctuates between 0.45⁰.55. Glide attrition as the mainly attrition pattern for each material, plow furrow and the abrasive dust were obvious on the surface of wears; with the Al₂O₃ content increases the wear weight loss of the compound materials tends to reduction,and more obvious when the Al₂O₃ content >5%. The abrasion resistance of compound materials made by sol-gel preparation was best, compared to pure molybdenum wear weight loss reduced 29% .