Chemical resistance coefficient

The forecast of RubCon chemical resistance coefficient for x = 10 years of operation in corrosive environments has been carried out by [21,24] according to these formulas ... 

It is evident that RubCon is a corrosive-stable structural material because its chemical resistance coefficient during 10 years of operation in aggressive environments exceeds 0.5. The obtained data allow determination of the thickness of the concrete cover of a reinforced RubCon structure. 

BaS04 of more than 3%, the chemical resistance coefficient Kcr of RubCon samples is increased (lines 3), whereas its compressive strength falls (line 2). 

Table 3.12 illustrates that the proposed adhesive composition is highly resistant to acidic environments at elevated temperatures. Reduction of epoxy resin of up to 6% leads to a decrease in adhesive strength up to 3.5 MPa, and an increase in its content of over 7.4% leads to a reduction in the chemical resistance coefficient of up to 0.81-0.83. 

Tetralluoroethylene polymer has the lowest coefficient of friction of any solid. It has remarkable chemical resistance and a very low brittleness temperature ( — 100°C). Its dielectric constant and loss factor are low and stable across a broad temperature and frequency range. Its impact strength is high. 

It resembles polytetrafiuoroethylene and fiuorinated ethylene propylene in its chemical resistance, electrical properties, and coefficient of friction. Its strength, hardness, and wear resistance are about equal to the former plastic and superior to that of the latter at temperatures above 150°C. 

The properties of high quaUty vitreous sihca that determine its uses iaclude high chemical resistance, low coefficient of thermal expansion (5.5 X 10 /° C), high thermal shock resistance, high electrical resistivity, and high optical transmission, especially ia the ultraviolet. Bulk vitreous sihca is difficult to work because of the absence of network-modifyiag ions present ia common glass formulations. An extensive review of the properties and stmcture of vitreous sihca is available (72). 

Lapple (in Periy, Chemical Engineers Handbook, 3d ed., McGraw-Hill, New York, 1950) presents an alternative form of Eq. (17-10) in which the gas-viscosity term is explicit instead of being incorporated into the resistance coefficients ... 

Smaii-tube Tefion Chemical resistance of tubes no tube fouling. Clean fluids, condensing, cross-exchange. Low heat transfer coefficient. 2.0-4.0... 

In addition to the presence of stable C—F bonds, the PTFE molecule possesses other features which lead to materials of outstanding heat resistance, chemical resistance and electrical insulation characteristics and with a low coefficient of friction. It is today produced by a number of chemical manufacturers such as Du Pont (Teflon), ICI (Fluon), Hoechst (Hostaflon TF), Rhone-Poulenc (Soreflon), Montecatini (Algoflan), Nitto Chemical-Japan (Tetraflon) and Daikin Kogyo-Japan (Polyflon). 

Include plastics with coefficient of friction, chemical resistance, and others. Many plastic materials inherently have a low coefficient of friction. Other plastic materials can incorporate this property by compounding a suitable ingredient such as graphite powder into the base material. It is an important feature for moving products, which provides for selflubrication. Chemical resistance is another characteristic that is inherent in most plastic materials the range of this resistance varies among materials. 

Fluorocarbons Very high heat and chemical resistance, nonburning, lowest coefficient of friction, high dimensional stability Injection molding Encapsulation Continuous pultrusion... 

The main characteristic of refractory oxides is their excellent resistance to oxidation. Their brittleness however makes them prone to thermal shock with the exception of silica which has a compensating low coefficient of thermal expansion. The chemical resistance of the major oxides deposited by CVD is rated in Table 17.7. 

C 531 Test Method for Linear Shrinkage and Coefficient of Thermal Expansion of Chemical-Resistant Mortars, Grouts, and Monolithic Surfacings C 579 Test Methods for Compressive Strength of Chemical-Resistant Mortars and Monolithic Surfacings... 

I. Platinum. Platinum (mp 1,769°C), is a malleable and ductile metal with high chemical resistance. Because of this resistance, it finds use in some laboratory ware. It is attacked by aqua regia, and, at somewhat elevated temperatures, by sulfur, phosphorus, halogens, and cyanide (in the presence of air). The coefficient of expansion for platinum nearly matches that of soft glass (flint glass), and an adequate seal between platinum wire and soft glass may be obtained. 

---