silicon nitride ceramic nitride NCX-5102 Saint-Gobain/Norton Industrial Ceramics

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hot isostatic pressing "The material produced is designated NCX-5102 and consists of a silicon nitride-4% yttria composition that is densified by glass-encapsulation HIPing. ... Large-scale batches (30 kg) of Si3N4-4% Y2O3 powder were milled in water, and the slurry was used to cast hundreds of tensile rods. The starting Si3N4 powder (Ube) was derived from a dimmide process. ... The net-shape-formed bars were HIPed using glass encapsulation (ASEA Cerma AB, Robertsford, Sweden). The HIP process was optimized using pressure, time and temperatures to assure full densification and development of an elongated microstructure for desired fracture toughness..." Si3N4·4wt%Y2O3 Si N Y O 4 % 972,561 23,1370 997,396 23,1370 540-1237,344-452 4,-,- Tensile,Flexural,Flexural 23,23,1370 665,653,517 1109,-,- 1109 Tensile 23 4 665 "Reliable Ceramics for Advanced Heat Engines," V.K. Pujari, D.M. Tracey, M.F. Foley, N.I. Paille, P.J. Pelletier, L.C. Sales, C.A. Willkens, and R.L. Yeckley, American Ceramic Society Bulletin, Vol. 74[4], pp. 86-90 (1995), published by American Ceramic Society Cautions 1. Data evaluated by acceptance criteria 2. "The nonlinear character of the distribution with multiple inflections suggests that a two-parameter Weibull fit of these data (sigma = 1038 MPa, m = 10.4) is inappropriate and that the multimodal nature of the data should be represented using competing risk analysis. ... The important feature of the three-parameter Weibull distribution is the existence of a threshold stress below which there is zero probability of failure." Flexural Strength MPa Tensile Strength MPa Weibull Modulus Weibull Strength MPa Literature survey The authors cite V.R. Pujari et al., "Development of Improved Processing and Evaluation Methods for High Reliability Structural Ceramics for Advanced Heat Engine Applications, Phase I," final report, ORNL/Sub/89-SB182/1, NTIS Rept. No. DE93-040528, August (1993), and summarize the procedure as follows. "The cylindrical buttonhead specimens were machined to ORNL design with a gauge diameter of 6.0±0.1 mm. ...50 mm diameter, 150 mm long specimens... were machined as many flexure bars (3 mm by 4 mm by 50 mm) for assessment of the properties across the 50-mm section." Test Temperature °C Range of Strengths MPa Weibull Modulus Threshold Strength MPa Stress Mode Weibull Strength MPa