【作者】 汪志健；

【导师】 刘爱国；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2006， 硕士

【摘要】 采用等离子熔化-注射技术(Plasma Melt Injection, PMI)制备出Fe/石墨型金属基固体自润滑表层复合材料,并对该材料的制备工艺、组织结构和性能进行了系统研究和分析。本文中运用正交试验设计等方法进行工艺试验的设计,以扫描速度、送粉量和送粉嘴直径作为可调参数,构成三因素三水平的正交试验。以粒子粒度(60～80目和20～40目)的影响构成单因素试验。运用X射线衍射仪进行物相分析,用金相显微镜和扫描电子显微镜对等离子熔化-注射层组织形貌进行观察,用能谱仪对等离子熔化-注射层进行成分分析,采用显微硬度仪对熔注层的显微硬度进行测量,采用摩擦磨损实验机对熔注层的耐磨性进行检测。试验结果表明送粉量相同时,提高扫描速度可以改善试件的外观形貌;扫描速度相同时,提高送粉量也可以改善试件外观形貌。扫描速度和送粉量都能对组织结构产生巨大影响,其中以送粉量的影响最为显著;提高扫描速度利于树枝状晶产生,提高送粉量利于石墨的产生。送粉嘴直径对试样的外观形貌和组织没有明显的影响。SiC颗粒的尺寸会对获得的组织产生重大影响,采用20～40目的SiC颗粒时组织中更容易形成石墨。等离子熔化-注射60～80目SiC所获得的组织为珠光体组织加非平衡组织,其非平衡组织中存在着大量的细小缩孔;熔合线上方存在着一条珠光体带。组织中的珠光体的显微硬度为HV675,非平衡组织的显微硬度为HV798。熔注层的耐磨性为Q235钢的4.1倍,磨损机理主要为磨粒磨损。等离子熔化-注射20～40目SiC所获得的组织为大量石墨球和非平衡组织加上少量的珠光体组织;石墨球分布于整个熔注层内;非平衡组织内部存在尺寸在纳米级的石墨球。组织中的珠光体的显微硬度为HV387,非平衡组织的显微硬度为HV358。熔注层的耐磨性为Q235钢的48.3倍,磨损机理主要为磨粒磨损。更多还原

【Abstract】 Production process, microstructure and properties of Fe/Graphite metal matrix self-lubricating surface composite produced by plasma melt injection (PMI) were investigated.In this thesis, orthotropic technology was applied to design engineering testing which was a three factors three levels orthotropic testing. The three factors included scanning velocity, powder flow and diameter of the nozzle of powder supplier. And particle size (60~80mesh and 20~40 mesh) was regarded as a factor to design monofactorial testing.XRD was applied to analysis substance. Optical microscope and SEM were applied to observe microstructure. EDX was applied for composition analysis. Hardness tester was applied to detect microhardness of layer and wear resistance tester was applied to detect wear resistance of the layer. The result shows that the morphology of specimen can be improved by increasing scanning velocity at constant powder flow, and it also can be improved by increasing powder flow at constant scanning velocity. Scanning velocity and powder flow both have notable influence on microstructure and the influence of powder flow is more powerful. The increasing of scanning velocity contributes to formation of dendrite. The increasing of powder flow contributes to formation of graphite. The nozzle diameter of the powder supplier has no obvious influence on the morphology and microstructure of specimen. Particle size of SiC has distinct influence on the microstructure and more graphite exist in the microstructure produced by PMI 20~40 mesh SiC particles.The constitution of microstructure produced by PMI 60~80 mesh SiC particles is pearlite and nonequlibrium which has a large number of sinkholes. The microhardness of pearlite is HV675 and the microhardness of nonequilibrium is HV798. The wear resistance of the layer is 4.1 times as good as Q235 matrix. Mechanism of wear is adhesion and abrasion. The constitution of microstructure produced by PMI 20~40 mesh SiC particles is a great deal of spherical graphite, nonequlibrium and few of pearlite. Distribution of spherical graphite is homogeneous. Nanometer scare spherical graphite has been found in更多还原