Abstract Processing, microstructure and tribomechanical performance of spark plasma sintering (SPS) processed α−SiAlON bonded tungsten carbide (WC) have been reported. SPS at 1750 °C under 40 MPa for 25 min resulted in almost theoretically dense composites. Microstructure analysis using scanning and transmission electron microscopy revealed formation of principally micron sized, equiaxed WC grains surrounded by sub-micron to micron sized α−SiAlON having both equiaxed (higher concentration) and elongated (lower concentration) grain morphology. Sharp and clean WC/α−SiAlON interface regions were noticed without any interfacial reaction product. As evidenced from elemental mapping under HAADF-STEM, the α−SiAlON grain boundary region was found to be rich in yttrium and oxygen, whereas, presence of characteristics elements were identified in α−SiAlON and WC grains. Addition of α−SiAlON in WC matrix resulted in progressive improvement in tribomechanical performance of the composites compared to pure WC. The 40 wt% α−SiAlON bonded WC matrix composite offered almost 30–33% higher Vickers hardness and toughness than those obtained for pure WC. Three point flexural strength of the 40 wt% α−SiAlON/WC composite was found to be around 425 MPa. Unlubricated wear tests also indicated significantly higher damage of hard and tough β−Si3N4 ball when sliding against the composites compared to pure WC. Formation of progressively thicker and adherent tribolayer containing broken particles of WC and α−SiAlON having sharp edges was possibly the primary reason that caused severe abrasive wear of the counterbody. Results indicated the efficacy of SPS processed α−SiAlON bonded WC composites having improved tribomechanical performance over conventional monolithic WC.

中文翻译：

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放电等离子体烧结处理的 α-SiAlON 结合碳化钨：致密化、微观结构和摩擦力学性能

摘要 放电等离子烧结 (SPS) 处理的 α-SiAlON 键合碳化钨 (WC) 的加工、微观结构和摩擦机械性能已有报道。SPS 在 1750 °C 和 40 MPa 下持续 25 分钟，产生几乎理论上致密的复合材料。使用扫描和透射电子显微镜进行的微观结构分析表明，主要形成微米尺寸的等轴 WC 晶粒，周围是亚微米至微米尺寸的 α-SiAlON，具有等轴（较高浓度）和细长（较低浓度）晶粒形态。观察到清晰干净的 WC/α-SiAlON 界面区域，没有任何界面反应产物。从 HAADF-STEM 下的元素映射证明，发现 α-SiAlON 晶界区域富含钇和氧，而，在 α-SiAlON 和 WC 晶粒中发现了特征元素的存在。与纯 WC 相比，在 WC 基体中添加 α-SiAlON 导致复合材料的摩擦力学性能逐步提高。与纯 WC 相比，40 wt% 的 α-SiAlON 粘合 WC 基复合材料提供了几乎 30-33% 的维氏硬度和韧性。发现 40 wt% α-SiAlON/WC 复合材料的三点弯曲强度约为 425 MPa。与纯 WC 相比，未润滑的磨损测试还表明，当与复合材料滑动时，坚硬且坚韧的 β-Si3N4 球的损伤明显更高。逐渐变厚且粘附的摩擦层的形成包含具有锋利边缘的 WC 和 α-SiAlON 破碎颗粒，这可能是导致配对体严重磨损的主要原因。