Authors: Noritaka Saito Hiroyuki Ikeda Yoshinori Yamaoka Andreas M Glaeser Kunihiko Nakashima
Publish Date: 2012/08/11
Volume: 47, Issue: 24, Pages: 8454-8463
Abstract
An effective joining strategy suitable for ultrahigh temperature ceramics will have to be developed for their wider application In the present study the wetting behavior of molten Ni–Nb alloys that will form during the transient liquid phase TLP bonding when a Ni/Nb/Ni interlayer is used to bond a HfB2 composite processed with MoSi2 addition was systematically investigated In addition a trial TLP bond of HfB2 composite with a Ni/Nb/Ni interlayer was also performed at 1500 °C Pure Ni was found to melt at a temperature well below its normal melting point during the heating period which is mainly attributed to the interfacial reaction between HfB2 MoSi2 and the droplet The contact angles of all Ni–Nb alloys rapidly decreased with time and showed good wetting against HfB2 composite Among them the pure Ni droplet totally disappeared around 1400 °C during heating SEM–WDS microstructural analysis on the cross section of the wetting sample revealed that the reaction layer contained multiple intermetallic compounds involving Si suggesting the reaction with the sintering aid MoSi2 With the 40 at Nb addition less interfacial reaction at the Ni–Nb alloy/HfB2 composite interface was observed Consequently it was revealed that a wellbonded interface was achieved when HfB2 composite was bonded using the Ni/Nb/Ni interlayerSome of the authors NS HI and YY acknowledge Dr Laura Esposito Dr Diletta Sciti and Dr Laura Silvestroni of CNRISTEC Faenza Italy for useful suggestions and fruitful discussion on the HfB2 composite processing One of the authors NS wishes to thank GrantsinAid for Young Scientists A of the Japan Society for the Promotion of Science JSPS under Contract No 21686071 AMG acknowledges the GRF for generous longterm support for fundamental work of this type
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