LASER ALLOYING OF PLASMA-SPRAYED MOLYBDEN UM LAYERS INTO STEEL SURFACES TO INCREASE WEAR-RESISTANCE

Investigations were carried out concerning laser alloying of molybdenu m on steel surfaces for increased weer. During the investigations, mol ybdenum was pre-deposited on the steel surfaces by plasma spraying and subsequently fused by means of Nd:YAG laser radiation (cw). To gain a n extended process understanding, a video camera; sound emission analy sis and a bond pyrometer were used for process monitoring. The alloyed zones produced were examined using different test methods, such as el ectron disperse X-ray analysis (EDX). Adhesive wear tests were carried out with a pin-on-disc apparatus. In this paper, the employed process equipment and results concerning laser alloying of different pre-depo sited molybdenum coatings will be presented. The process monitoring sy stem used is a suitable medium for defining the beam/material interact ion. Using the sound emission analysis, for example, if was possible t o qualitatively evaluate the crack intensity during allaying. The meas urements of the leading surface temperature of the molten pool using a pyrometer permits a correlation to the molybdenum content in the allo yed rone, which plays an important role with regard to crack intensity and wear behavior.