DEVELOPMENT OF CONTINUOUS FIBER REINFORCED REACTION SINTERED SILICON CARBIDE MATRIX COMPOSITE FOR GAS TURBINE HOT PARTS APPLICATION

ABSTRACT A dense silicon carbide matrix composite reinforced by HiNicalon fibers coated with boron nitride was fabricated by slurry impregnation and subsequent reaction sintering with molten silicon. The effect of the fiber coating structure and the infiltrating metal composition on the mechanical properties of the composite was investigated. The fabrication process for the combustor liner and the shroud segment for a 15 MW gas turbine was developed. The small combustor liner and the shroud segment with some machined notches were evaluated in a combustion test at 1773 K and atmospheric pressure. Excellent durability for gas turbine hot parts was recognized

Prevalence and Characteristics of TCFA and Degree of Coronary Artery Stenosis An OCT, IVUS, and Angiographic Study

AbstractBackgroundThe relationship between features of vulnerable plaque and angiographic coronary stenosis is unknown.ObjectivesThe purpose of this study was to systematically investigate the absolute number, relative prevalence, and characteristics of thin-cap fibroatheroma (TCFA) at different degrees of stenosis using optical coherence tomography (OCT), intravascular ultrasound, and coronary angiography.MethodsWe identified 643 plaques from 255 subjects who underwent OCT imaging in all 3 coronary arteries. They were divided into 3 groups on the basis of angiographic diameter stenosis: Group A (30% to 49%, n = 325), Group B (50% to 69%, n = 227), and Group C (>70%, n = 91).ResultsOCT showed that the absolute number of TCFA was greatest in Group A (n = 58), followed by Groups B (n = 40) and C (n = 33). However, the relative prevalence of TCFA was higher in Group C (36%) than in Groups A (18%) or B (18%) (p = 0.003 and p = 0.002, respectively). Fibrous cap of TCFA was thinner in Group C than in Groups A (p < 0.001) or B (p = 0.001). intravascular ultrasound showed that the plaque burden of TCFA was largest in Group C (80.1 ± 7.4%), compared with Groups B (67.5 ± 9.4%) and A (58.1 ± 8.4%). TCFA in Group C had a higher remodeling index than those in Group A (p = 0.002).ConclusionsThe absolute number of TCFA is 3 times greater in nonsevere stenosis than in severe stenosis. It is, however, twice as likely for a lesion to be TCFA in cases of severe stenosis than in nonsevere stenosis. Moreover, TCFA in severely-stenotic areas had more features of plaque vulnerability