U. D. Mannem, General Electric India Technology Centre Pvt Ltd., Bangalore, India; E. Kern, H. Weiss, Laboratory for Surface Engineering, Siegen, Germany
The starting powders Ti and TiB2 are cryo-milled to form composite particles. Cryo milling is performed in a horizontal Simoloyer mill from ZOZ GmbH, Germany. The milling parameters like process temperature, milling energy, milling time are optimized to get thermal spray grade free flowing feedstock. The composite powders, produced through mechanical alloying, have homogeneous distribution of the TiB2 (second) phase. The efficiency of the process to obtain thermal spray grade feedstock is > 90%. The composite feed stock is thermally sprayed onto plain carbon steel by HVOF spraying and Cold spraying. The microstructural difference in Ti-TiB2 coatings through these two spray processes is discussed.
Mechanical milling is the most efficient way to product composite powder feed-stocks for thermal spraying. The presentation in detail decribes how by changing the milling conditions, one can get either stable or metastable phases in the composite powders. Additionally the microstructural diffference in different spray techniques for the same feedstock is shown.
