Silicon tensile strength

The temperature range of general purpose material is approximately -50 to h-250°C but both ends of the range may be extended by the use of special purpose materials. Whereas the general purpose silicone compounds have a tensile strength of about 1000 Ibf/in (7 MPa) it is possible using fumed silicas to achieve values of up to 20001bf/in (14 MPa). Similarly, whereas the normal cured compounds have a compression set of 20-50% after 24 hours at 150°C, values of as low as 6% may be obtained with the special rubbers. 

Nonmagnetic drill collars are manufactured from various alloys, although the most common are Monel K500 (approximately 68% nickel, 28% copper with some iron and manganese, and 316L austenitic stainless steel). A stainless steel with the composition of 0.06% carbon, 0.50% silicon, 17-19% manganese, less than 3.50% nickel, 12% chromium, and 1.15% molybdenum, with mechanical properties of 110 to 115 Ksi tensile strength is also used. 

Aluminum drillpipe is generally made of 2014 type aluminum-copper alloy. Composition of this alloy is 0.50 to 1.20% silicon, 1.00% iron maximum, 3.90 to 5.0% copper, 0.40 to 1.20% manganese, 0.25% zinc maximum and 0.05% titanium. The alloy is heat treated to T6 conditions that represent 64 ksi tensile strength, 58 Ksi yield strength, 7% elongation and a Hbn of 135- Aluminum drillpipe generally comes with steel tool joints that are threaded on to ensure maximum strength that cannot be attained with aluminum joints. 

Similar types of lamellar morphologies were observed for triblock copolymers of diphenylsiloxane and dimethylsiloxane having 40 wt% polydiphenylsiloxane, using electron microscopy, 47-148>. The lamellae thickness was approximately equal to the chain length of the rigid polydiphenylsiloxane blocks. These copolymers showed elastomeric properties comparable to those of conventional silica-reinforced, chemically crosslinked silicone rubbers. Tensile tests yielded an initial modulus of 0.5-1 MPa, tensile strength of 6-7 MPa and ultimate elongation between 400 and 800 %. 

Figure 19.3. Tensile strength of CVD silicon-carbide fiber as a function of temperature.

Silanol-terminated PDMS and hexadecyltrimethylammonium-exchanged clay were used to prepare PDMS-clay nanocomposites via melt intercalation [90]. The melt intercalation nanocomposites did not achieve as high a reinforcement as the aerosilica silicone hybrid, but the nanocomposite formed from solution had a nearly identical reinforcing effect on tensile strength as the aerosilica composite. 

Yajima. S., Hayashi. J., Omori, M. and Okamura, K. (1976). Development of a silicon carbide fiber with high tensile strength. Nature 261, 683-685. 

Fig. I.IB illustrates fibers typical of commercial asbestos, while Fig. l.ll shows Fiberglas and Fig. I.IJ silicon carbide whiskers. Some of the fibers in these examples are bent, occasionally through 180°, indicating considerable flexibility. Whiskers of other compounds can also bend but the tensile strength of these materials is their most remarkable feature. The measured values (Table 1.2) are at least ten times higher than those observed for the same compounds in bulk or in another morphology (Walker and Zoltai, 1979). The numerous investigations into the causes of this unique response have produced several hypotheses.

An important application of polydimethylsilane is as a source of silicon carbide (SiC) fibres, which are manufactured under the trade-name Nicalon by Nippon Carbon in Japan. Heating in an autoclave under pressure converts polydimethylsilane to spinnable polycarbosilane (-Me2Si-CH2-) with elimination of methane. The spun fibres are then subjected to temperatures of 1200-1400 °C to produce silicon carbide fibres with very high tensile strengths and elastic moduli." As a result of their conductivity, polysilanes have also been used as hole transport layers in electroluminescent devices. In addition, the photoconductivity of polymethylphenylsilane doped with Cgo has been found to be particularly impressive. ... 

Yajima, S., Hasegawa, Y., Hayashi, J., and Iimura, M. (1978). Synthesis of continuous silicon carbide fibre with high tensile strength and high Young s modulus. J. Mater. Sci. 13, 2569-76. [2, 221]... 

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