Research On Ti-Al And TiN Coatings Prepared By Laser Cladding And Plasma Spraying

With the development of science and technology, the demand of the material properties in industry is higher and higher, intermetallic compound and ceramic phase of more and more concerned with excellent performance has been widely applied in various fields. Die steel with wear-resisting, high temperature resistant requirements needs surface treatment. Ti-Al and TiN coatings were prepared in steel surface by using laser cladding and plasma spraying in order to improve the performance of the material in the lower cost in this paper.Ti-Al powders and pure Ti were prepared by mechanical milling and then were studied by the differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) in this paper. The results were shown that: with the ball milling time increasing, powders particle size became smaller, however, there was no intermetallic compounds formed in this process.Ti-Al and TiN coatings were preparated in Q235 steel surface by using laser cladding and plasma spraying subsequently, phase and microstructure were studied by XRD and SEM,metallurgical bonding was formed in the coatings which were prepared by laser cladding, and mechanical activation by plasma spraying. Microstructure of the coatings which were prepared by mechanical milling was compact,grain size became low while the scaning speed increased. The hardness test, high temperature stability test and the corrosion test were completed. The result indicated that the hardness of the TiN coating was the highest. The hardness value of it was 1013.5HV with the power of 1200W and the scanning speed of 600mm/min, which was nine times of the matrix. The hardness value of it was 945.5HV with the power of 1000W and the scanning speed of 600mm/min.The highest hardness value of coating on Ti-Al which was prepared by plasma spraying was 535.67HV. The hardness value of laser remelting thermal barrier coatings increased with the scaning speed. The high temperature stability of the coating both of plasma and laser remelting thermal barrier process were excellent.The corrosion resistance on Ti-Al coating was about 600(kohm) with the power of 1000W and the scanning speed of 600mm/min. The corrosion resistance of the other coating was poor due to the porosity of their structure.