Study On The Production Of Three-dimensional Network Ceramic/Fe-alloy Composites And Its Abrasive Behavior

Three-dimensional (3-D) network ceramic/Fe alloy composites combine high strength and hardness, wear and oxidation resistance of ceramics with ductility as well as thermal and electrical conductivity of metals. Each phase contributes to the properties of the final composite. Potential applications for 3-D network ceramic/Fe alloy composite components are a large variety of wear parts in a range of market sectors including electronic waste recycling,mining and metal forming. Nowadays, the biggest difficulty to fabricate the co-continuous composites is to overcame three difficults, one is the poor wettability of ceramics by Fe metal melts due to the ceramic/Fe alloy is the non-wetting system, the second is the weak interfacial strength between ceramic and Fe alloy which can not transfer energy and thermal efficiently, and the third is the needful high-performance equipment duo to the high melting point of Fe alloys. In order to conquer the problems mention above, theoretical analysis worked with experimental were employed in this study. Consequently, 3-D network ceramic/Fe alloy composite was developed and carried out the wear and friction experiments. In this paper, a new technique , Ni-adulterated ceramics come with nickelic solution- chemical treatment and pressureless infiltration / sand mold casting, was employed. The result showed that three-dimensional (3-D) network ceramic/Fe alloy composites with high-strength interface were faberricated by this technique, and the composites has high wear resistance. The Ni-adulterated ceramics were developed by ball-milling with pressing/ oigins oganics impregnation and high temperature sintering technique.The Ni particles distributed uniform in the ceramics and some were connect with ech others.The new technique, nickelic solution- chemical treatment,was developed to coat the ceramics/ ceramic foam and ceramic particles. The result showed that a good coating was obtained and with this coating, the wettability between the ceramic and Fe melt was significantly improved.In manufacturing the 3-D co-continuous ceramic/metal composites, the pressureless infiltration was employed. In order to improve the understanding of the infiltration process, time-dependent infiltration experiments were performed and the obtained microstructures and ceramic/metal interfaces were characterised. The result showed that good bonding between ceramic and metal without cracks. A infiltration layer between the Ni particles in the ceramic and the matrix could be verified. The two phases , (Fe_xAl_y)₃O₄ and (Al_xCr_y)₂O₃ ,were characterised by XRD. Preliminary results on the infiltration of Ni-adulterated Al2O3 ceramic with molten Fe alloy showed that the three binding mechanisms of the interface between the ceramic and metal, mechanical connection, diffusionalbond and interfacial reaction, contributed to the predominant bonding strength,which was 63 MPa . In addition, the three composites with different Fe alloys, ceramic/ductile cast iron, ceramic/abrasion-resistant steel and ceramic/high chromium cast iron, were fabricated by sand mould casting technique using Ni-adulterated Al2O3 ceramic skeletons. The result showed that good bonding between ceramic and metal without cracks.The study on wear and friction experiments for ceramic/metal conposites were measured using the SRV testing machine. The wear mechanic was characteristic of oxidation wear basically and the average friction coefficient of the composites steady at low loads and friction frequencies, the 3-D co-continuous structure ceramics,which could prevent metal phase from heat-softening and carried the major load, leaded to better wear-resistence for composites than the corresponding metal matrix alloy because of the homogeneity interface bonding. For applied higher loads and friction frequencies, the analysis of the friction model incorporated with SEM examination of the on the worn composites surfaces reveals that the three wear mechanisms, including oxidation abrasion, adhesive abrasive and three-body abrasion, contributed to total wear depth which leaded to a higher friction level. Another criterion for wear behaviours was the hardness of metal matrix. In general, the composites with higher hardness of metal matrix leads to better abrasive resistance.