Kaihong Zheng

Interface Structure and Wear Behavior of Cr26 Ferrous Matrix Surface Composites Reinforced with CTCP

Using cast tungsten carbide particles (CTCP) and reduced iron powders as raw materials, the porous ceramic preforms with honeycomb, strip, and layer structure, respectively, were prepared by loose sintering process; then, the CTCP/Cr26 ferrous matrix composites were fabricated by casting infiltration process. The microstructure of the composites was analyzed by SEM, XRD, and EDS. The results show that a sintered shell forms as a result of the reaction of Fe and W2C in the CTCP during loose sintering process; the inner part of the shell around the CTCp consists of WC and Fe3W3C phases, while the outer part between the particles is dominated by Fe3W3C. Therefore, the strength of preforms is enhanced because the particles are connected with each other by sintered shell. During casting infiltration process, a transition layer constituted by WC and Fe3W3C formed at the interface of CTCp and the matrix due to the dissolution and precipitation of the sintered shell in the high-temperature liquid iron. The three-body abrasive wear behavior of the composites was investigated. The result shows the wear resistance of honeycomb structure composite is comparable to that of whole layer (WL) structure composite, which is three times of heat-treated Cr26. However, the honeycomb structure composite has higher performance/cost ratio owing to the lower CTCp volume fraction and higher strength and toughness compared with the WL structure composite.

Three-body abrasive wear resistance of iron matrix composites reinforced with ceramic particles

Pure aluminum oxide (Al2O3), ZrO2 toughened Al2O3 (ZTA; 25–30% ZrO2), and ZTA (55–60% ZrO2) ceramic particles reinforced Cr25 matrix composites are successfully fabricated by the infiltration casting process. The volume fraction of ceramic particles in the composites is 47–55%. The interface structure between ceramic particles and the matrix was analyzed by digital probing microscopy and was found to be continuous mechanical bonding. The wear behavior of the composites was studied by a three-body abrasive wear tester. ZTA (55–60% ZrO2) reinforced Cr25 composite has excellent wear resistance which is approximately six times higher than that of the high chromium cast iron matrix. It is discovered that the wear mechanism of composites is micro-cutting and fatigue stripping. A correlation exists between the wear resistance of composites and the strength of ceramic particles.