Don Lipkin - Academia.edu (original) (raw)
Related Authors
INDIAN AGRICULTURAL RESEARCH INSTITUTE, NEW DELHI, INDIA
Uploads
Papers by Don Lipkin
Journal of the American Ceramic Society, 2005
Using the technique of fluorescence piezospectroscopy, we determine the distribution of thermal r... more Using the technique of fluorescence piezospectroscopy, we determine the distribution of thermal residual stresses across the edges of three laminated aluminafzirconia com-posites. We develop a methodology for separating the measured stress state into microstresses that result from ...
Acta Materialia, 2014
ABSTRACT The durability of thermal barrier coatings (TBCs) deposited on Hf-modified B2 NiAl bond ... more ABSTRACT The durability of thermal barrier coatings (TBCs) deposited on Hf-modified B2 NiAl bond coatings has been investigated under thermal cycling conditions. The rate of bond coat oxidation and rumpling during thermal cycling was characterized and the cycles to failure measured. The location of cycling-induced cracks in the TBC multilayer was influenced by the bond coat composition but variation in TBC lifetime was small, despite the different failure modes. Analysis of the cycle-dependent degradation phenomena demonstrate a trade-off between rumpling resistance and interfacial toughness as a function of bond coat composition.
Surface and Coatings Technology, 2013
ABSTRACT The behavior of Hf-modified B2 nickel aluminide bond coatings, fabricated by ion-plasma ... more ABSTRACT The behavior of Hf-modified B2 nickel aluminide bond coatings, fabricated by ion-plasma deposition, has been investigated under thermal cycling conditions. The mass change, surface roughness, and microstructural evolution have been characterized. Variation in the Al, Cr, Pd and Pt concentrations did not affect the initial oxidation or rumpling behavior of these bond coats, but did influence oxide adherence as well as the surface roughness at failure. Both the Pt and, interestingly, the Pd-modified coatings displayed superior cyclic oxidation lifetimes compared to the state-of-the-art platinum aluminide coatings. The rate of surface roughening (rumpling) is discussed in terms of the B2 to L12 phase transformation and oxide spallation.
Astm Special Technical Publication, 1995
J Amer Ceram Soc, 2005
ABSTRACT Using the technique of fluorescence piezospectroscopy, we determine the distribution of ... more ABSTRACT Using the technique of fluorescence piezospectroscopy, we determine the distribution of thermal residual stresses across the edges of three laminated alumina/zirconia composites. We develop a methodology for separating the measured stress state into microstresses that result from grain-to-grain thermal mismatch and macrostresses that result from lamination-induced thermal mismatch between individual plies. Comparison between the measured edge-stress distributions and those calculated based on a simple force-superposition model shows good agreement, indicating that the laminate system is well approximated as linear elastic. Given the experimental confirmation of significant edge stresses in multi-ply laminates, the possibility of failure initiating at composite edges must be considered in the design of surface-compressed laminate structures with the aim of mediating the detrimental effect of surface flaws.
Journal of the American Ceramic Society, 2005
Using the technique of fluorescence piezospectroscopy, we determine the distribution of thermal r... more Using the technique of fluorescence piezospectroscopy, we determine the distribution of thermal residual stresses across the edges of three laminated aluminafzirconia com-posites. We develop a methodology for separating the measured stress state into microstresses that result from ...
Acta Materialia, 2014
ABSTRACT The durability of thermal barrier coatings (TBCs) deposited on Hf-modified B2 NiAl bond ... more ABSTRACT The durability of thermal barrier coatings (TBCs) deposited on Hf-modified B2 NiAl bond coatings has been investigated under thermal cycling conditions. The rate of bond coat oxidation and rumpling during thermal cycling was characterized and the cycles to failure measured. The location of cycling-induced cracks in the TBC multilayer was influenced by the bond coat composition but variation in TBC lifetime was small, despite the different failure modes. Analysis of the cycle-dependent degradation phenomena demonstrate a trade-off between rumpling resistance and interfacial toughness as a function of bond coat composition.
Surface and Coatings Technology, 2013
ABSTRACT The behavior of Hf-modified B2 nickel aluminide bond coatings, fabricated by ion-plasma ... more ABSTRACT The behavior of Hf-modified B2 nickel aluminide bond coatings, fabricated by ion-plasma deposition, has been investigated under thermal cycling conditions. The mass change, surface roughness, and microstructural evolution have been characterized. Variation in the Al, Cr, Pd and Pt concentrations did not affect the initial oxidation or rumpling behavior of these bond coats, but did influence oxide adherence as well as the surface roughness at failure. Both the Pt and, interestingly, the Pd-modified coatings displayed superior cyclic oxidation lifetimes compared to the state-of-the-art platinum aluminide coatings. The rate of surface roughening (rumpling) is discussed in terms of the B2 to L12 phase transformation and oxide spallation.
Astm Special Technical Publication, 1995
J Amer Ceram Soc, 2005
ABSTRACT Using the technique of fluorescence piezospectroscopy, we determine the distribution of ... more ABSTRACT Using the technique of fluorescence piezospectroscopy, we determine the distribution of thermal residual stresses across the edges of three laminated alumina/zirconia composites. We develop a methodology for separating the measured stress state into microstresses that result from grain-to-grain thermal mismatch and macrostresses that result from lamination-induced thermal mismatch between individual plies. Comparison between the measured edge-stress distributions and those calculated based on a simple force-superposition model shows good agreement, indicating that the laminate system is well approximated as linear elastic. Given the experimental confirmation of significant edge stresses in multi-ply laminates, the possibility of failure initiating at composite edges must be considered in the design of surface-compressed laminate structures with the aim of mediating the detrimental effect of surface flaws.