High-Temperature Flexural Strength

Effect of Temperature on Flexural Strength of TiB2 and TiSi2/MoSi2 Ceramics 

Material Composition (Wt%) Hot Pressing Temp. Relative Density (% pth) Grain Size (pm) Hexural Strength (MPa) RT 500°C 1000°C Ref. 

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Fig. 2.5 High temperature flexural strength of sialon (Si4 5Al15015N65-2%3Y203-5AI203) and silicon nitride (Si3N4-6% Y203-2% A1203) materials with and without SiC whiskers. Whiskers are from American Matrix.

The effect of different whisker types from various manufacturers on the high temperature flexural strength is shown in Fig. 2.6. As before, the strengths remain relatively constant up to 1000°C and decrease at higher temperatures. The decrease is most dramatic for the composite with whiskers from American Matrix. This is related to the relatively high impurity content of... 

Fig. 2.6 High temperature flexural strength of silicon nitride (Si3N4-6% Y2Oj-2%A12C>3) materials with various types of SiC whiskers. Whisker content was 20 vol.% for all composites. ACMC is Advanced Composites Materials Corp.

S. R. Choi and N. P. Bansal, High-temperature flexure strength, fracture toughness, and fatigue of zirconia/alumina composites, Ceram. Eng. Sci. Proc., 24 [3] 273-279 (2003). 

Hot modulus of rupture, HMOR the high-temperature flexural strength bending strength, measured at high temperatures. 

On the contrary, the high temperature flexural strength of TaB composites was strongly reduced compared to the room temperature value, which dropped from 630 to 220 MPa at 1200°C and to 115 MPa at 1500°C, owing to softening of significant amount of silica. The bad performances of tantalum-compounds at high temperature could also be related to the nasty nature of tantalum-oxide, which unavoidably forms and starts to volatilize above 1500°C. 

For the DSE LaB -TiB composite grown in the < 110> direction the coincidence of the slip planes in the matrix (110) and fiber (0001) phases is maximum (Hull Bacon, 2001 Kelly Groves, 1970). Therefore, the mutual plastic deformation occurs most easily and fracture resistance is nunimal especially at temperature higher 1200 C. As a result, the high-temperature flexural strength of such alloy decrease in the temperature range of 1400-1600 °C. 

The temperature factor 1.5 for HDPE-based composition was determined experimentally by measuring composite bottom rail and spindle flexural strength and flexural modulus at ambient temperature (70°F) and 130°F. The respective flex modulus values for bottom rails were 360,330 + 33,600 psi and 174,820 32,600 psi therefore, high temperature loss was 185,510 66,200 psi, or 51 9%. Similarly, for spindles the respective ambient- and high-temperature flexural modulus were... 

Grade G-11, glass fabric with heat-resistant epoxy resin binder, has properties similar to those of Grade G-10 at room temperature and, in addition, has high retention of flexural strength at elevated temperatures. 

Flexural Strength of High Performance Ceramics at Ambient Temperature," ia U.S. Mmry ProposedMilita Standard, MIE-STD-1942A., U.S. Army Materials Technology Laboratory, Watertown, Mass., June 1990 (supersedes MIL-STD-1942(MR) Nov. 1983). 

These LCT materials have very high tensile and flexural strength, and excellent mechanical and chemical resistance properties. Some commercial LCT are Vectra (Hoechst-Celanese) and Xydar (Amoco). Du Pont, ICI, GE, and Dow Chemical are also suppHers. Their appHcation in electronic embedding is stiU. in its infancy because of the high temperature processing requirement. Nevertheless, this class of thermoplastic polymers will play an important role in electronic embedding. 

For a high-temperature PEEK grade (PEEK-HT), compared to the value at ambient temperature, the percentage retention of tensile or flexural strength is roughly 15% at 250°C. 

Developers have used ASTM C-651-91, "Standard Test Method for Flexural Strength of Manufactured Carbon and Graphite Articles Using Four Point Loading at Room Temperature." Based on 2002 dollars and costs projected to high-volume production (500,000 stacks per... 

POM has a coefficient of linear expansion of 10.0 X 10 cm/cm C and high tensile, flexural, and compressive strengths. POM is attacked by adds but is resistant to alkalis and salts at room temperature. 

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