Gradient Wear-Resistant Composite Structure for Impact Toughness

The patent applies local quality by creating a gradient structure where the material composition varies spatially: the surface layer contains high proportion of hard phase particles (WC, TiC, TiCN, TiN) for wear resistance, while the interior contains more bonding phase for toughness. This is achieved through vacuum evaporation deposition of fine-grained wear-resistant material powder on coarse-grained particles, followed by selective dissolution of the deposited layer during sintering, creating a concentration gradient that provides both surface hardness and internal impact resistance.

The patent creates a composite material system combining hard phase particles (WC, TiC, TiCN, TiN) with bonding phase metals (Co, Ni, Fe, Cu, Mn, Cr, Mo, W, V). The composite structure allows the hard phase to provide wear resistance while the metallic bonding phase provides ductility and impact resistance. The gradient distribution ensures optimal performance by placing more hard phase at the wear-prone surface and more bonding phase in the interior to absorb impact energy.

The patent applies preliminary action by pre-coating the coarse-grained hard phase particles with fine-grained wear-resistant material powder through vacuum evaporation before sintering. This preliminary coating creates the gradient structure foundation, which is then finalized through controlled dissolution of the coating during sintering. This approach simplifies the overall process compared to attempting to create gradient structures during or after sintering, as the gradient is established in the green body stage and maintained through the sintering process.