C.H. Henager Jr et al Journal of Nuclear Materials 367-370(2007)1139-1143 sure exhibited reasonable strengths pplied pres- creep strength and corrosion resistance depending nd Al/AlO3 at 1473 K using 1 MPa on the structure and amount of free carbon shear testing at ambient temperatures of 21 MPa, [28, 29]. The low strength of the joint processed at 14.5 MPa, and 7 MPa, respectively, as shown in 1073 K in nitrogen suggests that a small amount Fig. 1. SEM micrographs of a Sic-filled PHMs of pressure and higher temperatures are required Hexaloy joint processed at 1473K in air is shown for adequate bonding. in Fig. 2. These joints possess reasonable shear The solid-state reaction joints for Hexaloy Sic strength values and are thin and dense after only between TiC and Si resulted in high strength joints I MPa applied pressure. Compared to similar joint prepared by others, these have the distinction of being slightly stronger and easier to process. Poly carbosilane requires inert handling and higher con version temperatures; however, it does convert to Sic whereas this polymer converts to a silicon oxy- carbide, which may be a disadvantage in terms of 1473K Fig. 3. Comparisons of joint shear strengths for Sic-filled PhMS (single-lap) with solid-state reaction joints of TiC t Si to form Ti,SiC2/SiC joints(double-notch). Solid-state reaction joints are AUSiC SiC (No 30 MPa applied pressure Fig. I. Single-lap shear strength of PhMs j Hexaloy SiC coupons processed in air at 1473K using I MPa pressure or in nitrogen with no applied pressure at 1073K. SiC Ti3SiC Fig. 4. TEM micrograph of joint f hexal Fig. 2. SiC-filled PhMS joints in polished cross-sections showing using the TiC-Si solid-state joining The original SiC clean joint/coupon interfaces and good joint densities for surface is marked with the Hexaloy Sic coupons this interface into the Ti] SiC/SiC joint regionand Al/Al2O3 at 1473 K using 1 MPa applied pres￾sure exhibited reasonable strengths in single-lap shear testing at ambient temperatures of 21 MPa, 14.5 MPa, and 7 MPa, respectively, as shown in Fig. 1. SEM micrographs of a SiC-filled PHMS Hexaloy joint processed at 1473 K in air is shown in Fig. 2. These joints possess reasonable shear strength values and are thin and dense after only 1 MPa applied pressure. Compared to similar joints prepared by others, these have the distinction of being slightly stronger and easier to process. Poly￾carbosilane requires inert handling and higher con￾version temperatures; however, it does convert to SiC whereas this polymer converts to a silicon oxy￾carbide, which may be a disadvantage in terms of creep strength and corrosion resistance depending on the structure and amount of free carbon [28,29]. The low strength of the joint processed at 1073 K in nitrogen suggests that a small amount of pressure and higher temperatures are required for adequate bonding. The solid-state reaction joints for Hexaloy SiC between TiC and Si resulted in high strength joints, Fig. 1. Single-lap shear strength of PHMS joints between Hexaloy SiC coupons processed in air at 1473 K using 1 MPa pressure or in nitrogen with no applied pressure at 1073 K. Fig. 2. SiC-filled PHMS joints in polished cross-sections showing clean joint/coupon interfaces and good joint densities for Hexaloy SiC coupons. Fig. 3. Comparisons of joint shear strengths for SiC-filled PHMS (single-lap) with solid-state reaction joints of TiC + Si to form Ti3SiC2/SiC joints (double-notch). Solid-state reaction joints are significantly stronger when processed at high temperatures and 30 MPa applied pressure. Fig. 4. TEM micrograph of joint region of Hexaloy coupon using the TiC–Si solid-state joining method. The original SiC surface is marked with the arrows and epitaxy is observed across this interface into the Ti3SiC2/SiC joint region. C.H. Henager Jr. et al. / Journal of Nuclear Materials 367–370 (2007) 1139–1143 1141