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Question
Category: Physical Methods
Subject: Platinum pastes - how is good adhesion achieved?
As a supplement to my earlier two questions on platinum metal pastes, I would like to know which organic platinum compounds may be mixed with the platinum metal paste to give good adhesion with an alumina substrate on firing?
Answer
Mix the platinum metal paste with ~ 2% Pb borosilicate glass powder and make into a paste. Together these will make a good bond with an alumina substrate on firing.
Fritted pastes should be fired at lower temperatures, typically around 700°C. Fritted pastes are typically used to attach platinum wires to the pure platinum layer that has already been deposited on the oxygen sensor substrate.
Answer posted January 2005
Submitted by: Dr Vipin Kumar
Affiliation: National Physical Laboratory, India
Answered by: Mr Tim Whiting
Affiliation: Development Manager, PCM and Ecat., Johnson Matthey