The Influence of Sintering Additives on the Fracture Behaviour and Wear of Liquid-Phase Sintered Polycrystalline Alumina

Abrasive wear of Al2O3–SiC and Al2O3–(SiC)–C composites with micrometer- and submicrometer-sized alumina matrix grains

“…Our previous works with calcium and magnesium silicate containing aluminas confirmed their high resistance against wet and dry erosion, which was much higher than in monolithic alumina. 17,28 The highest wear resistance observed in liquid phase-sintered nanocomposite TCS5G is the result of synergy of two effects: chemical interaction of silicate phases with alumina matrix grains, and the grain boundary strengthening hydrostatic thermal residual stresses of SiC nanoparticles always located, due to very fine size of the alumina matrix grains, in a close vicinity of grain boundaries.…”

“…The observed change of fracture mode from inter-to intra-granular in calcium and magnesium silicate containing liquid phase-sintered aluminas, although in our original work attributed to the presence grain boundary strengthening thermal stresses, seems to support the idea of the chemical effect of additives, especially silica, on mechanical behaviour of the ceramics. 17 Whatever is the mechanism responsible for higher grain boundary strength, chemical, or mechanical, higher energy required for initiation of the transgranular fracture leads to higher wear resistance of both nanocomposites and liquid phase-sintered aluminas. The effect is more pronounced in materials with SiC nanoinclusions, than in those containing only C particles, being highest in liquid phase-sintered aluminas containing SiC/C nanoparticles.…”

“…The calcia-to-silica molar ratio was set to 0.2, in accord with our previous results, which indicate excellent wet erosive wear resistance of polycrystalline aluminas of this composition. 17 A further 1 h mixing at room temperature was allowed for completion of hydrolysis, and the suspension was then dried under an infrared lamp. The dry powder was calcined for 60 min at 700 • C and passed through a 100 m mesh nylon sieve to provide a reasonably free-flowing powder.…”

Synthesis and two-step sintering behavior of sol–gel derived nanocrystalline corundum abrasives

“…17,18 To fabricate fine crystalline corundum abrasives by pressureless sintering route, grain boundary migration has to be abated. The grain growth can be controlled by two approaches: one is to prohibit grain growth by addition or dispersion of a second phase particles [19][20][21][22][23] ; the other is to control grain growth by a novel processing method. It was first reported that a two-step sintering (TSS) technique can be also used as an efficient route to attain a homogeneous microstructure and to decrease the number of closed pores.…”