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7179 |
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Tuesday, June 21, 2022, Saal Brüssel 11:40 AM Furnace brazing |
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Effects of joint design and interlayers on ceramic-metal joints |
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Kandarp Amin* / TWI Ltd., Great Britain Nick Ludford / TWI, Great Britain Madie Allen/ TWI, United Kingdom Christopher Hawkins/ DSTL, United Kingdom |
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The joining of dissimilar materials, such as ceramics and metals, is of significant importance in industries such as aerospace and automotive as an enabler for improving the operating performance of components. The challenge posed by such ceramic-metal joints is the mismatch in coefficient of thermal expansion that in turn creates thermally induced residual stress. This paper shares findings from a recent study that investigated the effects of joint design and use of interlayers to alleviate the residual stress between ceramic-metal joints. The base materials were alumina, silicon nitride and titanium and joints were formed using Ticusil® active braze. The ceramic and metallic specimens were manufactured in accordance with ASTM F19. The ceramic-metal joints were vacuum brazed and tested in accordance with ASTM F19. It was found that by reducing the contact area, through the use of knife edges, improvements in joint strength could be realised. Various knife edge geometries were tested and the best performing knife edge resulted in a significant improvement in average tensile strength when compared with a full face joint of an ASTM F19 specimen. The introduction of the interlayer resulted in a further significant increase in tensile strength. |