Wetting and reaction between beta '-sialon, stainless steel and Cu-Ag brazing alloys containing Ti

Joining of sialon to austenitic stainless steel has been carried out using active brazing alloys. Copper-silver eutectic alloys do not react with sial on at 900 degreesC and no wetting or chemical bonding occurs, however. it w as shown that copper-silver with addition of Ti to form active braze alloys , reacted chemically to cause wetting and chemical bonding. The surface act ive effect of indium in Cu-Ag based braze alloys results in different effec ts at the ceramic-braze and the steel/braze interfaces. The effect of indiu m in increasing the activity of titanium in Cu-Ag alloys results in enhance d reaction at the ceramic-braze interface, while at the steel-braze interfa ce the solubility and diffusion of metallic elements from the steel into th e braze alloy is limited and so the extent of reaction is smaller when indi um is present. The samples which were brazed at 950 degreesC gave good bend ing strength, and fracture occurred in the sialon indicating that the brazi ng process had produced an excellent interfacial bond. (C) 2001 Published b y Elsevier Science Ltd. All rights reserved.