RU2463321C1 - Antifriction composite material for making ship fittings - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to antifriction composite materials based on thermoplastic polymers and may be used in making highly loaded friction assemblies, particularly, to seals of ship ball valves. Material consists of (in wt %) aromatic partially crystalline linear polymer PEEK 450 PF with reinforcing filler from minced fiber of carbon fabric Ural T-22-30-35. Invention allows friction assembly bearing capacity of 0.8-4.0 MPa at sliding speed of 12 m/c to 0.5 m/s, water absorption of not over 2%, compression resistance of at least 250 MPa, ultimate stress at static flexure at least 160 MPa, and impact strength of at least 21 kJ/m².

EFFECT: improved performances.

5 dwg, 1 tbl, 2 ex

Description

The invention relates to antifriction composites based on thermoplastic polymers and can be used in various industries in the manufacture of high-stress friction units, in particular, seal elements of ball marine shutoff valves.

Known antifriction polymer composite materials based on polytetrafluoroethylene (Mashkov Yu.K., Poleschenko K.N., Povoroznyuk S.N., Orlov P.V. Friction and modification of tribosystem materials. - M .: Nauka, 2000. - 280 p.) containing coke powders (Ф4К20), molybdenum disulfide (Ф4М15), fiberglass (Ф4С15), coke and molybdenum disulfide (Ф4К15М5) as components. The tensile strength of these materials is in the range of 11-16 MPa.

Known anti-friction composite material (A.S. No. 1812190, IPC C08J 5/16), which contains, wt.%: Polytetrafluoroethylene 80-82; molybdenum disulfide 1-3; tin-lead bronze powder 5-12 and carbon filler 5-12. The carbon filler is a carbon fiber 0.05-0.50 mm long, obtained from carbonized carbon fiber material aged for at least 48 hours and dried and ground in the presence of polytetrafluoroethylene powder to fibers of the specified length. The tensile strength of this material is 22-24 MPa in tension, the wear rate during friction on a steel counterbody without lubrication is 0.065-0.068 mg / h at a sliding speed of 1 m / s, contact pressure 3 MPa.

The closest to the claimed composite material and adopted for the prototype is the material Grafelon-20M according to TU 2224-026-21065073-2003, which is currently used as a seal material in the nodes of ball valves. Grafelon-20M is an aromatic polyamide phenylone-C2 - 80% with a reinforcing filler of crushed fiber of carbon fabric brand TGN-2M - 20%. However, the material Grafelon-20M has a sufficiently large water absorption, leading to changes in the geometric dimensions of the locking unit and insufficiently high physical and mechanical properties.

The present invention is the creation of an antifriction material that provides the bearing capacity of the friction unit in the range from 0.8 to 4.0 MPa at a sliding speed of 12 m / s to 0.5 m / s, water absorption is not more than 2%, compressive strength not less than 250 MPa, tensile stress during static bending of not less than 160 MPa, impact strength - not less than 21 kJ / m ² .

The technical result of the invention, which provides a solution to the problem, is to improve the antifriction properties of the composite material, in particular, increase the compressive strength of the material, breaking stress during bending, and reduce the coefficient of friction and water absorption.

The technical result is achieved through the use of the claimed invention - an antifriction composite material, which is an aromatic partially crystalline linear polymer polyetheretherketone (PEEK) 450PF with a reinforcing filler of ground carbon fiber Ural T-22 with chemical treatment GOST 28005-88 (UTA).

Polyetheretherketones are aromatic polymers (polyarylene), the molecular chains of which are built from phenylene rings, carbonyl groups and oxygen atoms (Fig. 1) * (* Literature. 1. I.P. Losev, E. B. Trostyanskaya. Chemistry of synthetic polymers, third edition, 1971. 2. AXShaov, A. M. Kharaev, A. K. Mikitaev, A. Z. Kardanov, Z. S. Khasbulatova Plastic masses, 1990, No. 11. 3. I. Barvinsky , I.E. Barvinskaya. Handbook of injection thermoplastic materials).

The antifriction composite material contains the following ratio of components, wt.%: Polyetheretherketone (PEEK) 450PF with a dispersion of 95-110 μm and a bulk density of 0.6 g / cm ³ - 65-70% and ground carbon fabric Ural T-22 (UTA) with the following characteristics: breaking load - 1428 N (base), 1071 N (weft) and with a surface density of 335 g / m ² - 30-35%.

To obtain the claimed anti-friction material, its components were mixed in a dispersant, tableted and dried to remove excess moisture at a temperature of at least 120 ° C for 12 hours.

Then, the tabletted antifriction material from the oven was laid in a mold preheated to 340 ° C.

After laying the anti-friction material, the mold temperature was increased to 390-400 ° C without applying pressure; upon reaching the set temperature, a pressure of 20 kg / cm ^{2 was} applied. The exposure time was 10 minutes for each 1 cm ^{3 of the} resulting product.

Pre-cooling was carried out together with the press plates to a temperature of 340 ° C while maintaining a holding pressure (20 kg / cm ² ), when this temperature was reached, the pressure was increased to 140 kg / cm ² and the cooling rate was maintained at 1.5 ° C per minute. After that, they were pressed on the press equipment.

The claimed antifriction material can be used in the manufacture of highly stressed friction units for various purposes and the formation on its basis of sealing elements for ball valves with pressing directly into the annular cavities of metal billets or without pressing by hot pressing of the material.

The properties of the obtained antifriction composite material were evaluated according to the following parameters:

- the density according to GOST 15139 was determined on the samples in the form of a straight round cylinder with a diameter of 30 mm and a height of 50 mm by the weight method;

- water absorption according to GOST 4650 was determined on the samples in the form of a parallelepiped with a square base, the side of the base - 50 mm, height - 3 mm;

- destructive stress during compression GOST 4651 was determined on the samples in the form of a parallelepiped with a square base, the side of the base -10 mm, height 15 mm;

- the breaking stress at bending GOST 4648 was determined on the samples in the form of a bar of rectangular cross section with a thickness of 7 ± 0.5 mm, a width of 10 ± 0.5 mm and a length of 140 ± 2 mm;

- hardness according to GOST 4670 was determined on the samples in the form of a parallelepiped with a square base, the side of the base is -140 mm, height - 7 mm;

- impact strength according to GOST 4647 was determined on samples in the form of a bar of rectangular cross section, 4 ± 0.2 mm thick, 6 ± 0.2 mm wide and 50 ± 1 mm long.

For tribological tests, samples were made in the form of disks of antifriction material with a diameter of 30 mm and a thickness of 10 mm. As counters, we used 20X13 steel rollers with a diameter of 50 mm and a thickness of 10 mm.

The tests were carried out in clean tap water, as well as in an aggressive environment - synthetic sea water containing 7% of mechanical impurities - clay with sand. Sand fraction - up to 100 microns.

The test results of the obtained antifriction composite material, as well as the properties of the prototype are shown in the comparative table.

Recipe Destructive stress in compression, MPa Breaking stress, MPa Impact strength, kJ / m ² Brinell hardness, MPa Water absorption
reduction at 20 ° С,% Density, g / cm ³ Coefficient of friction in fresh water in synt. sea water Prototype Grafelon 20M 250,0 160 21.0 250 0.30 1,360 0.22 0.26 PEEK 450PF + 35% UTA * 278.0 160 20.9 290 0.05 1,322 0.11 0.16 PEEK 450PF + 30% UTA * 260,0 167 21,2 240 0.05 1,315 0.11 0.16 * -% content of crushed carbon fabric.

From the test results it is clear that the obtained material provides a solution to the problem.

The test description of the claimed composite material is supplemented by the following photographs:

figure 2 - experimental sample of material in the fixture of the universal testing machine TsDM-10;

figure 3 - an experimental sample of the material on the supports of the universal testing machine TsDM-10;

figure 4 - experimental sample of material installed in the bath with coolant;

5 is a universal machine of friction 2070 SMT-1.

Claims (1)

Antifriction composite material for the manufacture of seal elements for marine fittings, consisting of a matrix for which an aromatic polymer is used, and a reinforcing filler in the form of crushed carbon fiber fibers, characterized in that the aromatic polymer is an aromatic partially crystalline linear polymer - polyether ether ketone (PEEK) 450PF, and as a reinforcing filler - crushed carbon fabric brand Ural T-22, while the composition of the material contains the following ratio , wt.%:
polyetheretherketone 450PF 65-70 shredded carbon fabric Ural T-22 30-35

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