An advanced ceramic cutting tool material was developed by means of micro-scale SiC particle cooperating with nano-scale SiC particle dispersion. With the optimal dispersing and fabricating technology, this multi-scale nanocomposite may get both higher flexural strength and fracture toughness than that of the single-scale composite. The improved mechanical properties may be mainly attributed to the inter/intragranular microstructure with a lot of micro-scale SiC particles located on the grain boundary and a few nano-scale SiC particles located in the matrix grain. Because of the thermal expansion mismatch between SiC and Al2O3 resulting in the compressive stress on the SiC/Al2O3 interface, the interface bonding strength between Al2O3 and SiC was reinforced, which can compel the crack propagating into the relatively weak matrix when meeting the SiC particle on the boundary; while the alumina grain boundary is not the same strong as the SiC/Al2O3 interface and the Al2O3 grain, therefore the crack propagates sometimes along the Al2O3 grain boundaries and sometimes through the grains, when reaching to the nano-scale SiC particle inside the matrix, the crack was pinned and then deflected to the sub-grainboundaries. These coexisting transgranular and intergranular fracture mode induced by micro-scale and nano-scale SiC and the fining of matrix grain derived from the nano-scale SiC resulted in the remarkable strengthening and toughening effect.

In order to improve the machining efficiency of high strength steel 2.25Cr1Mo0.25V and tool life, intermittent turning performance of 2.25Cr1Mo0.25V with common carbide tools and advanced coated carbide tools was experimentally studied, cutting parameters and tool types were optimized. The results showed that the machining efficiency and tool life of advanced coated carbide tools were remarkably higher than that of common carbide tool; the tool life of quadrate coated tool was longer than that of circular tool. The cutting tool failure mechanisms were also discussed.

In order to improve the machining efficiency and tool life in manufacturing process of hydrogenation reactor shell components, the cutting performance of quadrate GC4235 coated carbide tool in intermittent turning 2.25Cr-1Mo-0.25V steel was investigated, the optimal cutting parameters were obtained. The empirical mathematical models of relationships among the amount of metal removal, tool life, cutting force and cutting parameters were established. The failure mechanism of the GC4235 carbide coated tools for turning 2.25Cr-1Mo-0.25V steel at lower speed intermittent turning was abrasive wear and the coating peeling; however coating peeling and substrate adhesive wear were the main failure forms at the higher speed.

In this paper, 3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) and TiN/3Y-TZP(adding TiN particles to 3Y-TZP) composites were fabricated by hot-pressing technique. Phase composition, microstructure and mechanical properties of the composites were investigated. It is shown that the flexural strength, fracture toughness and Vickers hardness of TiN/3Y-TZP was significantly improved by the addition of TiN particles compared with 3Y-TZP. The flexural strength of ZYT2 (20wt% TiN addition) is 1318 MPa. The fracture toughness of ZYT4 (40wt% TiN addition) is 16.8MPa·m1/2. The toughening and strengthening mechanisms were analyzed. The XRD results show that the additing of TiN can hinder the transformation from tetragonal phase to monoclinic phase of 3Y-TZP during fabrication process.

The interfacial energy and diffusion phenomenon of the Al2O3(012)-SiC (011) interface model are studied based on molecular dynamics. The interfacial energy increases firstly until reaches its maximum 0.459J/m2at the temperature of 1500K and then decreases. The relationship of diffusion coefficients for each kind of atoms is C>Si>O>Al. Diffusion coefficients of atoms increase at first and then decrease as the temperature goes up. This indicates the diffusion mechanism has been changed during the temperature rising process.