Silicone, a material with outstanding properties

Silicone, a material with outstanding properties

For decades, silicone has been a material that has led more and more engineers and technicians to create innovative solutions for medium and high voltage electrical products. Silicone has gained market share over comparable raw materials. For the low, medium and high voltage manufacturing industry, Dr. Dietrich Müller GmbH supplies stamped parts as well as molded parts made of silicone.

Silicone, silicone film, fluorosilicone and silicone foam are ideal for the electrical, aerospace, medical and pharmaceutical, automotive, sensor, housing and mechanical engineering industries as well as companies in the food, rail, metal and automation industries.

Silicone rubber

Silicone rubber is the collective term for a variety of elastomers which, starting from dimethyldichlorosilane, are formed by polycondensation of corresponding downstream products. Unlike organic rubbers, the molecular backbone of silicone elastomers does not consist of carbon, but is instead composed of alternating oxygen and silicon atoms. The vulcanization of VMQ is usually carried out with peroxides. To stabilize their mechanical properties, the vulcanizates must be annealed.
Silicone rubber offers good temperature resistance up to 280 °C, good low-temperature flexibility, and good ozone and weathering resistance. Its gas permeability at room temperature is higher than other rubbers, its electrical insulation properties are very good, and its physiological inertness is high.
Because of their advantageous properties, silicone rubbers are used as the basis for a wide variety of products, such as hoses and seals for the automotive sector or products for food processing, baking and cooking. VMQ can be found in sportswear and footwear as well as in electrical equipment and medical technology.

Resistances of silicone rubber

Chemical resistance:
– engine oils and gear oils of aliphatic type (e.g. ASTM oil No. 1)
– animal and vegetable oils and greases
– glycol-based brake fluids
– flame retardant hydraulic fluids HFD-R and HFD-S
– high-molecular chlorinated aromatic hydrocarbons
– water up to +100°C
– diluted salt solutions
– ozone-resistant, ageing-resistant and weather-resistant

Not resistant:
– superheated water vapor above +120°C
– acids and alkalis
– low-molecular chlorinated hydrocarbons (e.g. trichloroethylene)
– fuels
– aromatic hydrocarbons (e.g. benzene, toluene)

Solid silicone in various Shore hardnesses

Silicone is available from Dr. Dietrich Müller GmbH in Ahlhorn in various colors (such as red, black, green and white as well as blue) as well as in transparent versions. Stamped silicone seals are available in various Shore hardnesses from 20° to 80° Shore A and can be used at temperatures between -100° and + 300° C without any problems.

For rail vehicles we offer silicone according to EN 45545-2 with 50° and 60° Shore A.

Silicone foams as stamped parts

Silicone foam combines the high-quality properties of silicone with the flexibility of a foamed elastomer, thus enabling solution-oriented applications in many fields of use, especially in sterile environments. BISCO® BF 1000 silicone foam, BISCO® BF- 2000 silicone foam or BISCO® HT 800 silicone foam are used for corresponding applications.

Silicone foam square profiles

Silicone foam profiles are predominantly manufactured with closed cells. This results in a smooth closed outer skin. These silicone foam profiles can be self-adhesive on one side. Silicone foam profiles are elastic, deformable, compressible and have very good resilience. They are water repellent and repel organic substances. The outer skin remains intact even with repeated compression.

Flurosilicone

Fluorosilicone combines the good high and low temperature properties of silicone with good fuel and oil resistance. Fluorosilicone is thus particularly well suited for a wide temperature range to be covered and simultaneous exposure to aggressive substances such as gasoline or alcohol mixtures. Fluorosilicone rubber differs from pure silicone rubber (VMQ) in that some of the methyl groups have been replaced by trifluoropropyl groups. Corresponding compounds combine the inherently good swelling resistance of fluororubber (FPM) with the low-temperature flexibility of VMQ. FVMQ has comparable physical properties to silicone rubber. Both compound grades score equally on weathering resistance, ozone resistance and extreme low- and high-temperature resistance.

In terms of chemical resistance, however, fluorosilicone offers additional compatibility with aromatic mineral oils, fuels and low molecular weight aromatic hydrocarbons. Some of the fluorosilicone grades also exhibit improved compression set.

Thanks to its excellent media resistance, fluorosilicone rubber is particularly suitable for use in sealing technology. Among other things, it is used to manufacture O-rings, gaskets, hose liners (e.g. in turbocharger hoses) and diaphragms for automobiles, primarily for fuel systems at temperatures of up to 250 °C. Dr. Dietrich Müller GmbH manufactures the necessary stampings. Other areas of application include natural gas systems and natural gas conveying equipment, as well as aerospace technology. Because fluorosilicone compounds have a high shrinkage rate, manufacturing molds for products made from them often differ from those of other elastomers.

Fluorosilicone rubber O-rings (FVMQ)

In addition to the typical properties of normal silicone rubber, fluorosilicone rubber (FVMQ) exhibits even significantly improved resistance to oils, fuels and solvents. This applies in particular to aromatic and chlorinated hydrocarbons and alcohols. Applications for FVMQ O-rings therefore arise where resistance is required over a wide temperature range from -60 °C to +200 °C with simultaneous exposure to aggressive media, such as gasoline, alcohol mixtures, aromatic and naphthenic oils and a number of chlorinated solvents.

Special silicone solutions

There are many different ways to formulate solutions from silicone. We cooperate with the most well-known manufacturers of silicone formulations, who are always ready to develop special solutions for special projects.

 

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