Casting silicon

Impurities above maximum levels indicated in published specifications (42) can affect the properties of the finished casting. Silicon, for example, is normally added to many of the copper—beryllium casting alloys to promote fluidity, but excess silicon reduces ductility. Excessive zinc, tin, phosphorus,... 

A reinforcing filler, for example, highly dispersed silicon dioxide, is added to the mixture to produce vulcanizated material with improved strength. Cast silicone organic composites are widely used in electrical and electronic devices, in medicine, in the aircraft industry, etc., due to their ease of processing and the advantageous physical and chemical properties of the cured materials. 

The progress was considerably speeded up with the advent of cast silicon iron as the main acid-resistant metal [ I). Some other modern materials were also introduced into the construction of the equipment, such as enamel, tantalum, teflon [1 ] and glass [2]. Generally speaking the spent acid from nitration of glycerine, glycols and pentaery thritol have a tot in common althougli they differ in some particular points. The common problems of by-products of the nitration of alcohols will be discussed below. 

Another feature of this material is its narrow distribution of the fracture strength. When the strength distribution was expressed in Weibull statistics, the Weibull modulus was 46 - substantially higher than the value of 26 obtained for a conventional, self-reinforced silicon nitride. Thus, the seeded and tape-cast silicon nitride showed a synergistic improvement in all of the important fracture attributes, such as fracture strength, fracture toughness, and strength stability (Weibull modulus). 

Figure 8.7 Fracture toughness and strength of the seeded and tape-cast silicon nitride as a function of amount of P-seed costal addition. Reprinted with permission from Ref. [20] 1997, Elsevier Ltd.

Figure 8.16 R-curve behaviors determined by the AMDCB techniques for the seeded and tape-cast silicon nitrides with additives of 6.25 wt% Y2O3-1.0wt% AI2O3, 5wt%...

Figure 8.19 Fracture strength and fracture energies at room temperature (R.T.) and 1500°C of the seeded and tape-cast silicon nitride with Lu203-Si02 sintering additives and reference material (unseeded but otherwise...

Ultimate Tensile Strength of Investment Cast Silicon Carbide SCS-Al... 

Considering the final part to be manufactured (the whole reason why the tape is cast), consideration must be given to the firing atmosphere. It would not serve to use an excellent air burnoff binder for casting silicon carbide if the SiC will be fired in a reducing atmosphere. This is an especially important consideration when casting metal powders or other nonoxide powders. 

Kiourtsidis, G. and Skolianos, S. M., Corrosion Behavior of Squeeze-Cast Silicon Carbide-2024 Composites in Aerated 3.5 wt.% Sodium Chloride, Materials Science and Engineering A, Vol. 248, 1998, pp. 165-172. 

Buarzaiga, M. M. and Thorpe, S. J., Corrosion Behavior of As-Cast, Silicon Carbide Particulate-Aluminum Alloy Metal-Matrix Composites, Corrosion, Vol. 50, No. 3, 1994, pp. 176-185. 

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