(1. 東華大學(xué) 機(jī)械工程學(xué)院，上海 201620；
2. 東華大學(xué) 紡織裝備教育部工程研究中心，上海 201620；
3. 東華大學(xué) 材料科學(xué)與工程學(xué)院，上海 201620)
摘 要: 二階段燒結(jié)是一種通過(guò)控制燒結(jié)溫度變化以實(shí)現(xiàn)燒結(jié)樣品致密化過(guò)程中抑制晶粒長(zhǎng)大的燒結(jié)方法。以高能球磨法制備的納米WC-MgO復(fù)合粉末為原料，并采用二階段熱壓燒結(jié)法制備WC-MgO復(fù)合材料。研究二階段熱壓燒結(jié)對(duì)燒結(jié)塊體的致密度、晶粒大小和力學(xué)性能的影響，優(yōu)化二階段燒結(jié)中第一階段溫度t1、第二階段溫度t2及保溫時(shí)間θ等工藝參數(shù)，采用XRD和SEM對(duì)復(fù)合材料的組織形貌進(jìn)行表征。結(jié)果表明：當(dāng)t1為1 750 ℃，t2為1 550 ℃時(shí)能使WC-MgO復(fù)合材料的致密度達(dá)到99%(理論密度)，基體WC晶粒大小為2.59 μm，WC-MgO復(fù)合材料的維氏硬度提高到(18.4±0.5) GPa，WC-MgO復(fù)合材料的斷裂韌性提升至(12.95±0.5) MPa·m1/2，WC-MgO復(fù)合材料的抗彎強(qiáng)度提高至(1 283.7±126.6) MPa。
關(guān)鍵字: WC-MgO；二階段燒結(jié)；顯微組織；力學(xué)性能
（1. College of Mechanical Engineering, Donghua University, Shanghai 201620, China;
2. Engineering Research Center of Advanced Textile Machinery, Ministry of Education,
Donghua University, Shanghai 201620, China;
3. College of Materials Science and Engineering, Donghua University, Shanghai 201620, China）
Abstract:Two-step hot-pressing sintering (TSS) was applied to consolidate nanocomposite tungsten carbide-magnesia powders which were synthesized by high-energy planetary ball milling. A detailed investigation was carried out into the influence of TSS on the microstructure and mechanical properties of the WC-MgO bulk composites. Besides, the technique parameters of two-step hot-pressing sintering method, such as the initial highest sintering temperature (t1), second-step isothermal sintering temperature (t2) and holding time (θ) were studied in detail. The results show that, the sintering temperature plays an important role in densification and grain growth of WC-MgO composite. The optimum TSS regime consisted of heating at 1 750 ℃ (1st step) and 1 550 ℃ (2nd step), resulting in the formation of nearly full dense microstructure (99%, theory density) with suppressed grain growth (2.59 μm). As a result, the hardness, fracture toughness and flexural strength are improved to (18.4±0.5) GPa, (12.95±0.5) MPa·m1/2 and (1283.7±126.6) MPa, respectively.
Key words: WC-MgO; two-step sintering; microstructure; mechanical properties
