Laser Densification of Plasma Sprayed Refractory Metal Coatings on 4340 Steel.
Final rept. Jan 80-Mar 82,
AVCO EVERETT RESEARCH LAB INC EVERETT MA
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This program investigated the feasibility of surface melting and densification of plasma sprayed refractory metal coatings on SAE 4340 steel by means of a 15 kW CO2 laser. The refractory metals and alloys investigated were Tantalum, TA-IOW, Molybdenum and the Columbian base alloys WC 103 and WC 3015. True cladding, by melting of the plasma sprayed coatings, could not be achieved without damage to the substrate, or without alloying with the substrate. Partial melting or densification could be obtained, but pore formation and contamination by oxygen and nitrogen from the ambient atmosphere occurred in nearly all cases. It may, however, be possible to overcome these problems by improving the protective atmosphere used for the processing and by laser processing the refractory metals in the form of loose powder on the substrate surface rather than as a plasma sprayed layer. Cladding of SAE 4340 steel with Stellite No. 12 was also investigated. Good, fully dense continuous layers, approx. 0.07 in. thick, with a hardness of Rc 48-50, were obtained. Author
- Coatings, Colorants and Finishes
- Metallurgy and Metallography
- Fabrication Metallurgy