Faolit

Compared to other chemically resistant materials, faolite has several advantages. Under the influence of sunlight and electric lighting, the cured faulite darkens a little during the year, but the mechanical properties remain unchanged. Damaged Faolitic products are easily repaired on site, which is almost impossible for ceramic products. The use of faolite pipelines in winter conditions confirms the high frost resistance of the faolite.

Chemical Resistance

Faolite and faolitic products have a very high chemical resistance to acidic environments and organic solvents. The main qualitative characteristic of the faolite is high resistance to the action of acids (except acid oxidizing agents). It is resistant to acids:

• sulfuric (medium concentrations up to 50 ° C),
• hydrochloric (all concentrations up to 100 ° C),
• vinegar
• phosphoric (up to 80 ° C),
• lemon (up to 70 ° C).

It is also stable in solutions of various salts (up to 100 ° C), including sodium and calcium , in an atmosphere of gases: chlorine and sulfur dioxide up to 90-100 ° C. Faulite is unstable in nitric acid , hydrofluoric acid and alkalis ^[1] .

Physico-mechanical properties

Faolite is highly resistant to vibrations, shocks and sudden changes in temperature ^[2] . The material is twice lighter (density 1.5 ÷ 1.7 g / cm ³ ) and 4-6 times stronger than acid-resistant ceramics ^[3] . Main characteristics:

• The coefficient of thermal conductivity at 0 ÷ 100 ° C is from 0.25 to 0.9 kcal / m · h · deg.
• Faolite can be used at a higher temperature than many other acid-resistant plastics. According to the technical conditions, the heat resistance of the faolite is guaranteed up to 100 ÷ 130 ° C. Crude faulite can be molded at ordinary or slightly elevated temperatures without the use of high pressure. This allows you to make equipment from it, without the use of presses and expensive molds. Martens heat resistance - not less than 170 ° С.
• Brinnell hardness - 200 ÷ 400 MPa
• The coefficient of linear expansion at 20 ÷ 100 ° С - 2.3 · 10 ⁻⁵ K ⁻¹
• Impact strength - not less than 2.0 KJ / m ²
• Mass heat capacity - 1045 ÷ 1060 J / kg · K
• Scar fire resistance - 4 ÷ 5
• Dielectric strength - 3 ÷ 4 Sq / m
• Specific volume electrical resistivity - 10 ⁸ ÷ 10 ¹⁰ Ohm · m
• Adhesion to steel (bonding strength) - 0.51 ÷ 2.0 MPa.

Weaknesses

The main disadvantage of faolite is that its low impact strength and lack of elasticity in some cases leads to the need to increase the strength of faolitic products through the use of fabric interlayers (products from textofolite) or to place faolitic devices in steel casings. The poor thermal conductivity of the “A” grade faolite does not allow its use for heat exchange equipment. Faulite brand "T", having a higher coefficient of thermal conductivity, can be used in a number of such cases. The disadvantage of faolitization is the need for heat treatment in a special drying chamber, which complicates the use of faolite to protect the reinforcement in apparatuses with large dimensions.

With an increase in the temperature of the aggressive medium, the wear of the faulite increases as a result of a deeper penetration of chemicals into the faulite and partially its swelling. Behind the stage of swelling, the stage of destruction of the phaolite may occur - this depends on the aggressive environment and temperature. Sudden temperature fluctuations during the operation of the faolite are undesirable, as they can lead to the formation of cracks.

Faolith production consists of two main stages:

1. obtaining resol emulsion phenol-formaldehyde resin;
2. mixing resin with fillers.

Resin Formation

Resin formation occurs in a vacuum digester. In a certain dosage, Phenol , formalin and ammonia water are fed into the reactor, where the polycondensation of the reaction mixture takes place. The process lasts for 20-30 minutes at 90 ° C, until the mass is stratified into a resin and an aqueous layer. After that, the molecular weight is cooled in vacuum (at least 500 mm Hg. Art.). Water is removed from the reactor. The dried resin enters the mixer for the preparation of the faolite mass. The entire resin production cycle lasts up to 10 hours and makes it possible to obtain phenol-formaldehyde resin in the amount of 115-120% of the amount of phenol loaded ^[4] . The content of free phenol in the resin is not more than 10%, formaldehyde is not more than 2%, volatile is not more than 10% ^[5] .

Mixing Components

Liquid resole resin is heated to 50 ÷ 60 ° C and placed in a mixer. Fillers and additives are loaded, depending on the brand of the manufactured faolite:

• For grade A - 95 ÷ 165 parts by weight are added per 100 parts by weight of resin. antophilitic asbestos, 5 ÷ 10 parts by weight of chrysotile asbestos and from 0 to 3 parts by weight of stearin ;
• For grade T - 20 ÷ 26 parts by weight of chrysotile asbestos and 80 ÷ 105 parts by weight of graphite are added to 100 parts by weight of resin ^[4] ;
• For grade P , 35 parts by weight of chrysotile asbestos, 135 parts by weight of sand and 3 parts by weight are added to 100 parts by weight of resin. stearin ^[5] .

Each brand of faolites may differ in recipe depending on the purpose. At present, brand B Faolite is produced on the basis of talc . ^[6]

To increase the acid resistance of the faolite, asbestos is treated with hydrochloric acid, washed and dried to remove acid-soluble products. The mixing of the components is carried out for 1 hour. To maintain the temperature, hot water is supplied to the “jacket” of the mixer.

Finished Product

The resin imparts plasticity to the composition before curing and hardness after curing. Methods of processing it into semi-finished products (sheets, pipes), finished pressed products, and methods for making putty from it are based on the plasticity property of raw faolite.

Finished raw material can be used as a faolite putty, as well as for the manufacture of sheet and shaped products.

• Sheets are obtained by rolling at a given temperature and calendering at a given gap.
• Pipes are obtained by extrusion of a heated rolled mass.
• Shaped products are made by pressing ^[4] ..

The resulting products are subjected to curing in special chambers with a gradual increase in temperature from 60 ÷ 70 ° C to 120 ÷ 1300 ° C, produced by supplying steam for 25 ÷ 30 hours. When the temperature drops to 60 ÷ 700 ° C, the sheets or products from the chamber are unloaded. The surface of the faolite products is covered with bakelite varnish (alcohol solution of phenol-formaldehyde resin) in the bath. The lacquer coating is additionally cured in the chamber in approximately the same mode as the faolite products. ^[7]

Faolite is used as a heat-shielding and acid-resistant material ^[2] . Faitholite products can be assembled from individual parts made from cured faulite sheets and pipes. Sheets and products made from raw faolite are cured to transfer the resin to a non-melting and insoluble state, after which they become suitable as an acid-resistant material in chemical apparatuses, pipelines.

• Faitholite putty is used to seal joints during the assembly of faolitic bathtubs, equipment and fittings, as well as for faulitizing surfaces.
• Raw faulitic sheets are intended for corrosion protection of apparatus surfaces and the formation of various acid-resistant products: planks , bathtubs, pipes, etc. The inner surfaces are protected by lining , and the outer surfaces are faitolized.
• Hardened Faolith sheets are designed to protect rectangular containers and oxygen baths from corrosion.
• Faolite pipes are used in enterprises with aggressive environments. For example, a tower with a textolite pipe is used to remove gases and vapors from the pickling department of the mill at the Chelyabinsk Metallurgical Plant (pipe height 60 m, internal diameter 1.5 m). The drawbars of the pipe are made of brand T faolite with reinforcing calico impregnated with bakelite varnish.
• Shaped parts and fittings for pipelines, pump parts are made of faeolite mass by extrusion, molding and pressing and are used to transport aggressive liquids and gases ^[8] .

Textofaolite

Textofaulite is a material consisting of several layers of phaolite with layers of fabric laid between them. There are fabrics based on glass fibers (fiberglass, fiberglass), on the basis of cotton fabrics (calico, calico , belting ), on the basis of carbon, grafted or some other fabric. Due to the use of fabrics, products made of textofolite become 1.5-2 times stronger than products made of faolite. Textofaolite is used for the manufacture of large-sized ventilation pipes up to 200 m high, operating under severe conditions of exposure to various aggressive environments.

Faolithing