不锈钢等离子渗铪并固体渗碳后的高温摩擦性能

High-temperature Wear Properties of Austenite Stainless Steel with Plasma Surface Hafniuming and Carburization

目的提高0Cr18Ni9Ti奥氏体不锈钢的抗高温摩擦性能。方法利用等离子渗金属技术在不锈钢表面等离子渗铪,之后进行固体渗碳,在HT-500型球-盘磨损试验机上进行高温摩擦磨损实验,分析其高温摩擦性能及摩擦机制,并与不锈钢基体试样及不锈钢渗铪试样进行对比。结果渗铪试样的渗层厚度约为45μm,渗铪+渗碳试样的渗层厚度达100μm。渗铪+渗碳层弥散分布着许多粒状和短棒状碳化物颗粒,碳化物类型主要为MC型、M7C3型和M23C6型。基材的摩擦曲线波动起伏大;渗铪试样的摩擦系数较大,但磨损微观表现平稳;渗铪+渗碳试样的摩擦系数最小。磨损失重由大到小依次为:基材>渗铪试样>渗铪+渗碳试样。在300,500℃下,渗铪试样的耐磨性相对基材分别提高至1.47倍和1.94倍,渗铪+渗碳试样分别提高至2.13和2.28倍。基材划痕尺寸宽且较深;渗铪试样的表面硬度提高,且摩擦磨损过程中出现了合金氧化物;渗铪+渗碳试样的表面硬度高,基体韧性好,仅出现了很浅且窄的磨痕。结论通过等离子渗铪及离子渗铪+固体渗碳,均能提高不锈钢表面的抗高温摩擦性能,相比之下,离子渗铪+固体渗碳的效果更好。

Objective To improve high-temperature wear properties of 0Cr18Ni9Ti austenite stainless steel. Methods Wear properties of stainless steel （ substrate for short） , and the substrates after treatment with plasma surface hafniuming and carburiza-tion were investigated on HT-500 ball-disc wear tester. The high-temperature friction properties and friction mechanism were ana-lyzed and compared with those of the stainless steel substrate and stainless steel with surface hafniuming. Results The thickness of Hf-alloyed layer was 45 μm, and that of Hf＋C layer was 100 μm. The Hf＋C layer dispersed a large amount of granular particles and short sticks of carbide, and the main types of carbide were MC, M7 C3 and M23 C6 . The wear curve of the substrate showed large fluctuation, the Hf-alloyed sample had greater friction coefficient but the wear microstructure was stable; the Hf＋C-treated sample had the minimum friction coefficient. The wear loss was in the order of substrate＆gt; Hf-alloyed sample＆gt; Hf＋C-treated sam-ple. The relative wear resistance of Hf-alloyed sample at 300 ℃ and 500 ℃ were 1. 47 and 1. 94 times of the substrate, while that of Hf＋C-treated sample was about 2. 13 and 2. 28 times of the substrate. The scratches of the substrate were wide and deep. The surface hardness of Hf-alloyed sample was improved, and alloy oxide was generated during the friction wear process. The Hf＋C-treated sample had high surface hardness and the matrix had good toughness, the scratches were shallow and narrow. Conclusion Hafniuming and carburization could improve the high-temperature wear properties of the surface of 0Cr18Ni9Ti austenite stainless steel, and Hf＋C-treated sample showed better wear performance.