Anti-abrasive Wear Composite Of Carbide Eutectic/Cu-Mn-Ni Cupronickel

One of the main researching and developing aspects of composite materials in recent years is the using of composite materials in abrasive wear conditions. The demands on the engineering materials used in abrasive wear conditions are getting higher and higher, because of continuous progressing of the modern industry. The traditional anti-abrasion materials, such as white cast irons, high manganese steels, high chromium cast irons, ceramic particle/light metal composites, are no longer met the requirements of servicing conditions which becoming tougher and tougher. A new anti-abrasion composite invention is based on the rational selection of both the hard reinforcement particle and the metallic matrix.In this dissertation, the eutectic tungsten carbide and chromium carbide are chosen as the reinforcement phase of the composite while the cupronickel Cu-Mn-Ni as the matrix of the composite, and the metallurgy basis and mechanic properties of the above materials are carefully considered and analyzed. Through a hot-pressing technique, a dense composite with a well reinforcement particle distribution and 0⁴5% volume fraction of reinforcement particle is obtained. And a comparison test between the new composite material and a traditional anti-abrasion alloy, Cr28 cast iron, is made with a two body abrasive test. The following conclusions can be made through this research:1) The eutectic tungsten carbide and chromium carbide are an ideal reinforcement phase for anti-abrasion composite due to their satisfactory hardness and reasonable fracture toughness.2) The values of K_IC of the eutectic tungsten carbide and chromium carbide can be calculated through the measuring of the fracture length along the depression craters, which is supported by the fracture mechanics of ceramics. Such data is very vital for the wear rate modal establishment.3) Besides of the quenching-tempering and deforming-tempering processing, the cupronickel Cu-Mn-Ni can also be strengthened through a direct casting-tempering processing, tempering temperature 400⁴70℃ , withalloying element variation of 20³5%Mn. So, the cupronickel can be used as matrix material for anti-abrasion composite.4) The mechanism of the cupronickel tempering is that the rearrangement of the solution element atoms and the precipitation of MnNi phase, which the solution atom rearrangement will take a prolonged period of time and the precipitation of MnNi phase is the main reason of the strengthening.5) A new wear rate prediction modal for composite materials used in abrasive environments is proposed in this dissertation. Besides of the hardness, which is conventionally considered in the wear modal, other mechanical properties like fracture toughness Kjc, elastic modules E, the joint strength between the reinforcement phase and the matrix are also taken into account in the new modal to make the new modal more accurate in wear process representation.6) When the abrasive grit pressing depth x is much larger than the average reinforcement particle size Dm, x> >Dm the wear of the hard reinforcement particles is mainly in the form of departing from the matrix, while x<