等离子喷涂碳化钛-硅化钛涂层的组织结构与性能

Microstructure and Properties of Plasma Sprayed Titanium Carbide-Titanium Silicide Coatings

摘要:

研究直接喷涂和反应喷涂合成的两种碳化钛?硅化钛复合涂层的组织结构与性能．通过等离子喷涂技术将两种不同复合粉（TiC-TiSi₂和Ti-SiC）分别喷涂在TC4钛合金表面制备成碳化钛?硅化钛复合涂层，利用X射线衍射仪、扫描电子显微镜、万能拉伸试验机、显微维式硬度计、划痕仪对所得涂层进行表征及测试．结果表明：等离子喷涂TiC-TiSi₂复合粉所得涂层中含TiC为58%，Ti₅Si₃为21%，TiSi₂为7%，Si为9%和SiO₂为5%，等离子喷涂Ti-SiC复合粉所得涂层含有TiC（47%），Ti₅Si₃（40%）和SiC（13%）；在等离子喷涂过程中Ti-SiC复合粉中的Ti与SiC发生了明显的化学反应，反应生成了TiC和Ti₅Si₃；等离子喷涂Ti-SiC复合粉所得涂层，具有更薄的层片和更小的晶粒尺寸．与等离子喷涂TiC-TiSi₂复合粉所得碳化钛?硅化钛涂层相比，等离子喷涂Ti-SiC复合粉所得碳化钛?硅化钛涂层具有更高的结合强度、更高的显微硬度（提高了18.7%）、更好的韧性及更好的耐划痕性能，这主要在于等离子喷涂Ti-SiC复合粉反应合成的碳化钛?硅化钛涂层中硬质相的相对含量更高且反应合成的碳化钛、硅化钛晶粒更细小．

Abstract:

The microstructure and properties of two titanium carbide-titanium silicide composite coatings obtained by ex-situ and in-situ approaches were studied. Titanium carbide-titanium silicide composite coatings were prepared on the surface of TC4 titanium alloy utilizing plasma spraying TiC-TiSi₂ and Ti-SiC composite powders， respectively. X-ray diffractometer， scanning electron microscope， universal tensile testing machine， micro-Vickers hardness tester and scratch tester were used to characterize and test the coatings. The results showed that the coating obtained by plasma spraying TiC-TiSi₂ composite powders contains TiC （58 wt.%）， Ti₅Si₃ （21 wt.%）， TiSi₂ （7 wt.%）， Si （9 wt.%） and SiO₂ （5 wt.%）. The coating obtained by plasma spraying Ti-SiC composite powders contains TiC （47 wt.%）， Ti₅Si₃ （40 wt.%） and SiC （13 wt.%）. During the plasma spraying process， chemical reactions occurred between Ti and SiC in Ti-SiC composite powders， then TiC and Ti₅Si₃ were generated. The coating obtained by plasma spraying Ti-SiC composite powders had thinner lamina and smaller grain size. The coating obtained by plasma spraying Ti-SiC composite powders had higher bonding strength， higher microhardness （increased by 18.7%）， better toughness and better scratch resistance than the coating obtained by plasma spraying TiC-TiSi₂ composite powders. The main reason for the elevated mechanical properties could be concluded as the higher relative contents of the hard phase and the smaller grain size of titanium carbide and titanium silicide derived from the in-situ reactions.