TWI Industrial Member Report Summary 450/1992
I A Bucklow, J H Potter, S B Dunkerton
The work, part funded under the CEC EURAM initiative, was specifically aimed at producing 80 ceramic-faced steel tappets for trials in a Peugeot car test engine. Peugeot (France) and Johnson Matthey were partners in the programme.
It was necessary to braze the ceramic (Syalon 101) to the steel and so the major problem to be overcome was the large difference, between the two materials, in thermal contraction during cooling from the brazing temperature. Strain accommodation by solid interlayers of intermediate property materials, by thin convoluted discs of nickel or iron, and also by titanium honeycomb, was explored. A brazing programme to produce a satisfactory brazed joint at the same time as achieving a specified steel hardness was formulated, and shear testing of the completed joints was carried out.
Finite element analysis (to be reported separately) was employed to assist in the selection of interlayer materials and in the design of the convoluted discs.