Surface Treatment of Powder Metallurgical Compacts

Introduction Powder metallurgy (p/M) is a rapidly expanding technology for manufacturing of structural parts. The PA4 process provides economical as well as technical benefits over conventional processing of wrought material. It is possible to fabricate high quality, complex parts to close tolerances without machining. The energy consumption is low and the material utilisation and productivity high. The unique ability of P/M to obtain a uniform microstructure and to fabricate alloys and composite materials, which are otherwise d f i d t to make, increases the interest and research in the field. Fatigue, wear and corrosion are the three most “ m o n failure problems encountered in the industry. Recently, fatigue has been investigated extensively, but wear and corrosion problems of PiM part have been paid only little attention. The application of P/M parts has in many cases been restricted to non corrosive and wear free environments. Solving the wear and corrosion problems of P/M parts, increases the number of potential industrial applications. Surface treatment has been successfully applied to wrought materials to obtain better surface properties, but many of the commercial surface treatments used on wrought materials can not be used directly for the porous P/M parts. For example, electrolyte trapped in the pores during electroplating, could later cause serious corrosion attacks. The present work has concentrated on improving the corrosion resistance of P/M compacts by electrolytic surface treatment.