摘要表面改性技术是采用化学、物理方法改变材料或工件表面的化学成分或组织结构以提高机器零件或材料性能，包括耐磨、耐蚀以及抗氧化能力等的一类热处理技术，该技术现已被广泛应用于工业生产中。激光熔覆技术是材料表面改性其中一种技术，可以在低成本材料表面熔覆一层性能较好涂层，从而改变基体材料的各种特性。82247

本试验采用自动送粉方法在45#低碳钢表面激光熔覆Ni基合金粉末制备非晶复合涂层，并使用超景深数码显微镜和纳米压痕仪对涂层进行组织观察和纳米压痕性能测试，较为系统地研究了不同热输入下激光涂层显微组织及性能特征的影响。实验结果表明，Ni基合金粉末激光熔覆涂层显微组织，在基体/熔覆层界面生成了平面晶，胞状晶和柱状树枝晶，随后发生柱状晶向等轴晶生长转变，在熔覆层中部主要由非晶相、NbC颗粒相以及等轴晶相组成。对比基体硬度，纳米压痕下涂层中非晶相最多，同时有高强度、高硬度的金属间化合物NbC等化合物存在，因而增强了材料的硬度。

毕业论文

关键词：激光熔覆，Ni基，非晶涂层，显微组织，纳米压痕

Abstract

Surface modification technology is the use of chemical, physical methods change material or workpiece surface chemical composition or structure to improve the machine parts or material properties, including wear, corrosion and oxidation resistance ability of a kind of heat treatment technology, the technology is now is widely used in the industrial production。 Laser cladding technology changes the surface to which a technology can be in a low cost surface cladding layer performance better coating, thus changing the properties of the matrix material。

Uniform performance 45# with automatic powder feeding method in low carbon steel surface by laser cladding of Ni based alloy powder for preparing amorphous composite coating, and the use of ultra-depth of field digital microscopy and nanoindentation instrument on the coating microstructure and nano indentation test, a more systematic study of the different heat input of laser cladding layer microstructure characteristics。 Experimental results show that Ni based alloy powder laser cladding layer microstructure， matrix/cladding interface generates a flat crystal, cell shape and columnar dendrites, followed by growth of columnar to equiaxed transition, in Central cladding layer is composed of amorphous phase, NbC particulate phase and cubic phase。 Comparison matrix hardness, nanoindentation amorphous cladding layer is the most, and high strength, high hardness of the intermetallic compounds NbC and other compounds exist, thus enhancing the hardness of materials。

Keywords: Laser cladding,Nickel based,Amorphous coating,Microstructure,Nano indentation

目录

第一章 绪 论 1

1。1引言 1

1。2课题研究目的及意义 1

1。3国内外发展现状 1

1。3。1激光熔覆 1

1。3。2激光熔覆材料体系 4

1。3。3非晶材料 7

1。3。4纳米压痕技术 9

第二章 试验设备及试验方法 11

2。1激光熔覆镍基非晶涂层的制备实验 11

2。1。1基体材料 11

2。1。2熔覆粉末 11

2。1。3涂层制备工艺 11

2。2激光熔覆镍基非晶复合涂层组织观察