Teflon - a synthetic polymer material, widely used in chemical, electrical and food industry primarily as coatings.Its advantages include primarily the use of a wide range of temperatures and a low coefficient of friction.
Definition and types
Fluorines refers to several types of fluorine-containing plastics.The most common industrial and household use polytetrafluoroethylene.Depending on the manufacturer, this material may be called differently.In specialty stores selling Russian including imported PTFE.The material produced in the United States, referred to as "Teflo", in England - "Flyuon" Germany "Gostaflon".Here in Russia it is known as Teflon-4.
Other varieties of this material is not widely distributed but is also quite popular.It:
- polytrifluorochloroethylene (Teflon-3);
- polyvinylidene fluoride (PTFE-2);
- Other copolymers of fluorinated ethylene.
method of manufacturing
get all these species by chemical means.In fact, they are polymers to which fluorine atoms are added.Hence their name.
Teflon-4 is synthesized as a white powder and then pressed and sintered at high temperature.Other brands of this material is usually prepared by quenching.
When producing many innovative uses of modern products is PTFE.Specifications really just wonderful.The advantages of this material include:
- High chemical resistance.Teflon-4 does not dissolve even in boiling aqua regia.
- inertness and low porosity.
- very low coefficient of friction.This indicator Teflon has remained virtually unchanged at all temperatures.
- excellent dielectric properties.Quarantine this material is even at 200 grams.
- stability.The chemical properties of PTFE-4 remain unchanged at temperatures up to -300 m.
- Flame resistance - another advantage of a material such as Teflon.Features (heat-resistant polymer is characterized by the ability to self-extinguishing), it allow you to use it in places with high fire risk.
- Gas tightness.
- biocompatibility.This type of plastic commonly used in the manufacture of prostheses.
Disadvantages fluoroplast
As you can see, the material is very high quality and almost universal - Teflon.Features it has just wonderful.However, of course he has some disadvantages.To those include:
- high cold fluidity.This property limits the use of several fluoroplastic electronics.
- Ability to release hazardous substances when heated above 300 grams.
- more in comparison with other polymers, and the weight is not too good wear resistance.
Where Used
Teflon is used in many areas of the economy.Very often it is used:
- in the automotive industry.Since the coefficient of friction of this material is very small, because it produced high-quality bearings, friction units, support columns, and so on. D.
- In the electrical and electronics industries.PTFE insulator and is excellent.Therefore, it is very often used in the manufacture of cables, circuit boards, electronic components and so on. D.
- medicine.In addition to prostheses and implants made of polytetrafluorethylene storage capacity of serum and plasma.Produced therefrom and packaging drugs.
- in the food industry.This material very well suited, for example, for making dough rolling rolls used in bakeries, pumps for dispensing milk and m. G. Teflon on the inside surface of the pan - it is also one of the varieties of fluoroplastic.
- When assembling the water mains and sewer systems (FUM tape).
Thus, the material is very high demand, and in some cases simply irreplaceable - Teflon.Features (its applicability is actually very broad), provided for the guests, we consider below.
friction coefficient
This indicator Teflon has very little.The kinetic and static coefficient of friction against steel he is only 0.04.However, as already mentioned, the PTFE - the material is not too hard-wearing.Therefore, even after 100 passes the surface properties vary.The static coefficient of friction increases up to 0.13, and kinetic - up to 0.08.
Undergoes irreversible changes fluoropolymer surface and at a very high speed sliding.In this case, the coefficient of friction is increased by 2-3 times.The value of this indicator can vary greatly from temperature fluctuations.
reduces the friction coefficient fluoroplastic can load increases.So, for example, at a pressure of:
- 20-30 kg / m2 value of this indicator - 0.1;
- 150-300 kg / m2 - 0.02.
material is soft enough - Teflon.Its characteristics are such that when used for the manufacture of, for example, bearings, it is necessary to add powdered fillers.This can be coke, glass, molybdenum disulfate, and so on. D.
optical properties of thin films of Teflon in freely transmits light, ie transparent.He looks about the same as polyethylene.In thick films of this material is illuminated.
index fluoroplast transparency for UV rays depending on the variety of 2000-4000 A, for infrared - wavelength range from 2 to 7,5 μ.
High temperatures
When heated over 327 degrees fluoroplast its crystals are destroyed, causing it goes into the amorphous form.Normally thick parts made from this material are opaque.After the transition in amorphous form PTFE begins to freely transmit light.This material is not viscous and highly elastic.When heated to 415 degrees C and above its decomposition process begins.That is viscous Teflon does not happen at any temperature.
This affects the manufacturing process technology details of it.Polyacetal (specifications GOST defines as accurately as possible) can not be used for processing by traditional methods for plastics.For example, a product manufactured therefrom by injection molding or extrusion impossible.Produce parts and components of this material for sintering technology using compressed at low temperatures, "pills".
chemical properties of Teflon-4 is a chemically stable substance.This material does not dissolve even in very aggressive substances - diluted and strong acids.Do not exert any influence on him and concentrated alkaline solutions.
The only thing he does not tolerate the contact - are solutions of alkali metals in ammonia and elemental fluorine and chlorine trifluoride.Manifested action of these chemicals at elevated temperatures.
expansion coefficient
This parameter F4 PTFE characteristics is also just fine.However, its coefficient of expansion varies with temperature.As it is shown in the table.
| Temperature (C) | expansion coefficient |
| -60 to -10 | 8h10-5 |
| Up +20 | 25h10-5 |
| Up +50 | 11h10-5 |
| from +100 to +120 | gradually increases to 10h15-5 |
| +200 to +210 | increases to 21h10-5 |
recrystallization
As already mentioned, one of the shortcomings that have Teflon (characteristics that are generally good), is quite a high degree of cold flow.In practice, it is expressed in a modified form products made of it at elevated pressure.If they are used at not too high temperatures - from 80 to 100 degrees C, the load on them should not be more than 10 kg / m2.With more pressure on the product will be noticeable deformation.With increasing temperature, and the load should be reduced.
under strong pressure (100-200 kg / m2) sample made of polytetrafluorethylene, can be crushed in the plate thickness decreased by 3-5 times depending on the temperature.When deformation of the material normally does not occur, and it is cracking it causes no other damage.
table below you can see what is in the plan Teflon specifications (compression under certain loads).
| Temperature (C) | Load kgf / cm2 | degree of deformation (%) | factor | |
| 1 day | 4 hours | |||
| 20 | 33 | 6.00 | 6.25 | 0.03 |
| 20 | 21 | 3.05 | 3.19 | 0.032 |
fotoroplast can be used for the manufacture of parts used, and at greater than 30 kg / m2 pressure.However, in this case the structure of nodes in the product interface should be as dense.It is not allowed in the presence of her cavities or significant gaps.In this case, fluoroplastic will simply have nowhere to escape.Material Teflon - not too flexible.Therefore, in order to achieve a tight fit, it is added in the production of rubber.Sometimes the nodes contiguity use special spring compensators.
Teflon: specifications
In the production of PTFE-4 necessarily comply with the requirements of GOST 10007-80.The following table summarizes the most important physico-chemical properties of this material.
| Properties | parameter |
| Operating Temperature (C) | -269 ... +260 |
| thermal conductivity (W / m.grad at room temperature) | 0.25 |
| Melting point (C) | +327 |
| Elongation at break (%) | 350 |
| pressure requiredfor breaking the tensile (MPa) | 20-30 |
| coefficient of friction (on steel) | 0.2 |
| Water absorption per day | 0 |
|
Brinell hardness (MPa) | 30-40 |
| Density (kg / m3) | 2100-2200 |
That has such wonderful Teflon-4 specifications.The properties of this material make it suitable for the manufacture of parts of the highest quality.
Stamps PTFE-4
As mentioned, polytetrafluoroethylene - the most popular form of this type of polymers.Currently it produces several brands of PTFE 4:
- F-4PN.Used for manufacturing products with increased reliability.
- F-4D.It is used in the manufacture of products for general use.
- F-4D.This brand of PTFE makes thin-walled tube, insulation for cables, hoses and FUM tape.
- F-4D.Very manufacturable material used for the manufacture exact size.
Sheet Teflon
Products of this type are highly in demand in modern industry.For the production of electrical insulation, anti-friction and sealing products have a very good polymer like Teflon, specifications.Leaf variant of manufacturing technology is classified into:
- material brand "C" (sliced);
- mark "P" (compressed).
sale a Teflon rolls without coil.Its thickness is also determined by the guests and depending on the width can be 2-4 mm.
Teflon whose specifications are just excellent - a modern material used for the manufacture of a variety of components and parts.In comparison with conventional plastics it has a lot of advantages.Both the PTFE and articles thereof, in view of the high quality requirements, must be made in strict accordance with GOST.
