Powderlike composite filler and a method for preparation thereof

FIELD: composite materials.

SUBSTANCE: invention concerns powderlike composite filler suitable for elastomer materials intended for manufacturing articles operated under elevated wear or dry friction conditions. Filler particles contain at least one core made from ceramic material (metal carbide) and exterior layer made from polytetrafluoroethylene, volume fraction of cores in filler particles ranging from 1 to 10%. Powderlike composite is prepared by activating metal carbide particles in mechanochemical activator at mechanical power supply intensity between 1 and 5 kW/kg and dose 30 to 1000 kJ/kg in a medium selected from: air, nitrogen, argon, vacuum between 10-2 and 1 atm until particles with average size not larger than 15 μm are obtained, after which polytetrafluoroethylene is added to mechanochemical activator and metal carbide particles are modified at mechanical power supply intensity between 0.05 and 0.5 kW/kg and dose 3 to 100 kJ/kg in a medium selected from: air, nitrogen, argon, vacuum between 10-2 and 1 atm.

EFFECT: addition of powderlike composite filler to rubber compound results in reduction in friction coefficient under dry friction conditions and significant reduction in summary friction pair wear under hydroabrasive wear conditions.

4 cl, 2 dwg, 3 tbl

 

The present invention relates to fillers for elastomeric materials, working in conditions of increased wear or dry friction.

Know the use of fillers in the form of a powder of ceramic materials, namely metal carbides: titanium carbide, chromium carbide, tungsten carbide, in rubber compounds to obtain a wear-resistant products (EN 2230077, 08J 7/12, 2002). Due to weak adhesion of metal carbides with polymer matrix carbide metal in the rubber compound used in conjunction with a dispersion of polytetrafluoroethylene in mineral oil.

This way of introducing a filler that requires a liquid phase, is not suitable for creating many of the compositions, preferably a wear-resistant filler to enter in the composition in powder form, having adhesive properties to the polymer matrix.

Know the use of filler in the form of a powder of titanium carbide in the compositions of polytetrafluoroethylene, polyurethane, nitrile rubber, forecasters, polyphenylensulfide in the form of a dispersion in the Nickel-chromium matrix (US 3713788, SM 7/28, 1973), Nickel-chrome with additions of molybdenum and carbon matrix (US 4432883, SM 7/28, 1984).

The disadvantage of the filler is not sufficiently high adhesion of the filler with the polymer matrix.

Know the use of e is atomarray matrix metal carbides in the form of particles with a size of 0.1-10 μm in the shell of polycarboxylic or policylevel compositions or combinations thereof. Powder filler is produced by the interaction of particles of carbide metal polycarboxylate or polysilane components in the liquid phase and subsequent drying at a temperature of 80-100° (US 5527849, SC 3/14, 1996, US 5665807, SC 3/14, 1997).

As a prototype of the selected composite filler in powder form and method thereof disclosed in the description of the patent specification GB 2244489, SC 9/06, 1991 Filler contains a single particle, at least one core of inorganic material, for example of ceramic material, and a shell made of silicone elastomer which is the reaction product of monofunctional siloxane and secondary multifunctional silane. The connection of the core with the shell chemical.

The method of obtaining the specified filler includes bringing in the interaction of particles of inorganic material and liquid polysiloxane and Milanovich components, applying the obtained reactive liquid on the surface of the particles of inorganic material by stirring in a stirrer - mixer drum with the addition of solvent.

The specified filler is well distributed in the polymer matrix, allows to obtain high-quality products, but as the shell includes a shell made of a polymer derived from silicon rubber, and not alleged the manufacture of the shell of the other polymer materials. This method provides for producing composite filler in the form of powder in the shell from the liquid phase and does not allow you to get the filler in the shell of the solid phase.

The objectives of the present invention are expanding the range of fillers having high adhesion to the elastomeric matrix, with the shell not only of polymers on the basis of silicone rubber, and a method of obtaining a composite powder filler in the form of a carbide of the metal shell, which is made from a solid phase.

These problems are solved by creating a composite filler in powder form, the particles of which contain at least one core of a ceramic material and a shell of polymer, in which the ceramic material contains a carbide of the metal, and polymer shell it contains polytetrafluoroethylene, and the volume fraction of nuclei in the particle composite filler is from 0.1 to 10%. As the carbide of the metal, it can contain a carbide selected from the series: titanium carbide, silicon carbide, tungsten carbide, tantalum carbide, niobium carbide. The particle size of the composite filler is not more than 50 μm.

The method of obtaining the proposed composite filler in powder form lies in the interaction of the particles of ceramic material and a polymer, in the cat the rum particles of ceramic material in the form of carbide metal trigger in mechanochemical activator with the intensity of the supply of mechanical energy from 1 to 5 kW/kg and a dose of from 30 to 1000 kJ/kg in the environment, chosen from a number of: air, nitrogen, argon, vacuum pressure of 10-2to 1 ATM, to obtain particles with an average size of not more than 15 μm. Then the activator is injected polymer in the form of polytetrafluoroethylene and modify carbide particles of metal with the intensity of the supply of mechanical energy from 0.05 to 0.5 kW/kg and a dose of from 3 to 100 kJ/kg in an environment selected from a number of: air, nitrogen, argon, vacuum pressure of 10-2to 1 ATM.

The invention is illustrated by drawings, where figure 1 presents a composite filler in powder form with a single core-shell, figure 2 - composite filler in powder form with multiple nuclei in the shell.

Composite filler comprises at least one core 1 and sheath 2. The core 1 is made of carbide metal shell 2 is made of polytetrafluoroethylene. As the carbide of the metal can be used carbides of titanium, silicon, tungsten, tantalum, niobium. The volume fraction of nuclei in the particle composite filler is from 0.1 to 10%.

The method of obtaining the proposed filler implemented as follows.

Carbide particles of metal are placed in the working chamber of mechanochemical activator together with grinding bodies. Volume chamber, the volume of the grinding bodies, the dynamic characteristics of mechanochemical activator selected so as to ensure that interest is the intensity of the supply of mechanical energy to the processed material. The activation process was performed at room temperature with the intensity of the supply of mechanical energy from 1 to 5 kW/kg in an environment selected from a number of: air, nitrogen, argon, vacuum pressure of 10-2to 1 ATM. The required dose summed mechanical energy in the range from 30 to 1000 kJ/kg is achieved by processing at a given intensity. The activated receive carbide particles of metal with an average size of not more than 15 μm.

Then after a boot device in the working chamber of the mechanical activator is administered polytetrafluoroethylene granules with an average particle size up to 100 microns. The number of input polytetrafluoroethylene must correspond to the volume fraction of polymer in the final product. Dynamic parameters of mechanochemical activator (frequency and amplitude) change in such a way as to ensure the intensity of the supply of mechanical energy to the processed material in the range of 0.05 to 0.5 kW/kg Required dose summed mechanical energy in the range from 3 to 100 kJ/kg is achieved by a sufficient duration of processing at a given intensity. The environment in which the processing of carbide metal selected from range: air, nitrogen, argon, vacuum pressure of 10-2to 1 ATM.

As a result of processing of carbide particles get metal composite fill the ü in the form of powder, particles which contain the carbide metal coating of polytetrafluoroethylene.

As a matrix, use of a composition based on BNR, ethylene-propylene rubber, butyl rubber, fluorinated rubber.

The invention is illustrated by the following examples.

Carbide particles of metal with a particle size of from 10 to 80 μm and an average particle size of 50 microns is placed in the working chamber of mechanochemical activator together with grinding bodies - a set of metal and/or agate balls ranging in size from 3 to 15 mm in diameter and activate the modes (the intensity of the supply of mechanical energy, the composition of the processing environment), which are listed in table 1. The activated receive carbide particles of metal with an average size of which is given in table 1. Through a boot device in the working chamber of mechanochemical activator impose additional polytetrafluoroethylene granules with an average particle size up to 100 microns. Characteristics of the modification process of carbide metal (intensity, dose supply mechanical energy to the processed material), as well as the processing environment shown in table 1. The size obtained after processing of particles and volume fraction of nuclei in the particle of the filler shown in table 1. Particle size was determined using semimetrics analysis.

The obtained composite material input is whether in the rubber mixture based on butadiene-nitrile rubber SKN-26, filled with technical carbon (120 parts by weight), it was molded workpiece and vulcanizable products. Samples obtained from the specified rubber mixtures containing the inventive composite filler and without it (control sample), were investigated on the machine end friction MTT-2 at sliding velocity of 4.4 m/s, normal load 16 and 19.2 N without lubrication (dry friction) and on the plant, simulating friction axial bearing stage submersible pump ESP. Testing of the lower washer impeller (NSRC) was performed at the stand for accelerated tribological testing of elastomeric bearings degrees with the vertical location of the pump Assembly. Experimental pump consisted of a 5-speed manual ESP 5-50, made by powder metallurgy. The material response NSRC details - clamp guide vanes (BSEARCH)- powder steel Ggrd. The concentration of the abrasive material in the fluid was 0.2% (2 g/l). Comparative values of velocities of the wear test samples NSRC obtained in pumping mode 50 m3/day. Test duration for each group of samples NSRC was 6 hours. The coefficients of friction under conditions of dry friction are given in table 2. Frictional properties of samples in terms of hydroabrasive wear are shown in table 3.

From the data presented in table 1, it is seen that the present is invention allows to obtain a composite filler in powder form, the particles of which contain at least one core carbide metal coating of polytetrafluoroethylene, which has adhesion to the polymer matrix, the proposed method of manufacturing a composite powder filler by treating carbide metal solid polymer is polytetrafluoroethylene.

From the data presented in table 2 and 3, it is seen that the introduction of a composite filler in powder form in the rubber mixture leads to a decrease of the coefficient of friction under conditions of dry friction and a significant reduction in the total wear rate of the friction pair in terms of hydroabrasive wear.

Proposed by the present invention a composite filler in powder form expands the range of fillers, with adhesie to the polymer matrix, which enable the production of their use of wear-resistant under conditions of dry friction and abrasive wear of elastomeric materials, and the proposed method for the specified filler allows to obtain a composite filler in powder form, the particles of which contain at least one core of the carbide of the metal, and a shell of a polymer made from a solid phase.

Table 1.

Characteristics of the method of obtaining a composite powder in which omnitele.
The intensity of the supply of mechanical power, kW/kgDose of mechanical energy, kJ/kgPressure, ATM.The average particle size, micronsThe volume fraction of nuclei in the particle filler, %The resulting structure filler
# exampleCarbide metalWhen activatedWhen modificationsWhen activatedWhen modificationsWednesdayWhen activatedWhen modificationsAfter activationAfter modification
124567891011121314
1TiC20,05300100The vacuum10-210-215402,0Powder filler in the PTFE membrane
2TiC20,21000 30Nitrogen115408,0Powder filler in the PTFE membrane
3SiC10,5303The air1110509,6Powder filler in the PTFE membrane
4WC50,051000100Argon115401,6Powder filler in the PTFE membrane
5TaC50,051000100The vacuum10-210-25400,2Powder filler in the PTFE membrane
6NbC40,0550050Argon115400,2Powder filler in the PTFE membrane

Table 2
The coefficient Tr is of in conditions of dry friction.
# exampleLoadThe coefficient of friction
Without fillerContent filler
10 parts by weight20 parts by weight
Control160,25
NYY19,20,28
2160,080,11
19,20,12is 0.135
3160,140,155
19,20,160,175
4160,110,12
19,20,1250,13

Table 3
Frictional properties in terms of hydroabrasive wear
IndicatorsTest caseExample 2 according to the invention
Content filler
10 parts by weight20 parts by weight30 parts by weight
The average wear rate NSRC, µm/h3,140,250,180,17
The standard deviation of the wear rate NSRC,µm/h3,260,10,080,11
The average wear rate BSEARCH, µm/h17,116,714,319,4
The standard deviation of the wear rate BSEARCH, µm/h32,4the 15.612,1of 5.4
The total wear rate pairs NSRC-BSEARCH, µm/h20.2416,9514, 48mm19,57

1. Composite filler in powder form, the particles of which contain at least one core of a ceramic material and a shell of polymer, characterized in that the ceramic material contains a carbide of the metal, and polymer shell it contains polytetrafluoroethylene, and the volume fraction of nuclei in the particle filler is from 1 to 10%.

2. Composite filler in powder form according to claim 1, characterized in that as the carbide of the metal it contains a carbide selected from the series: titanium carbide is, silicon carbide, tungsten carbide, tantalum carbide, niobium carbide.

3. Composite filler in powder form according to claim 1 or 2, characterized in that the particle size of the filler is not more than 50 μm.

4. A method of obtaining a composite filler in powder form, the particles of which contain at least one core of a ceramic material and a shell of polymer, which consists in the interaction of the particles of ceramic material and a polymer, characterized in that the particles of ceramic material in the form of carbide metal trigger in mechanochemical activator with the intensity of the supply of mechanical energy from 1 to 5 kW/kg and a dose of from 30 to 1000 kJ/kg in an environment selected from a number of: air, nitrogen, argon, vacuum pressure of 10-2to 1 ATM, to obtain particles with an average size of not more than 15 μm, after which the activator is injected polymer in the form of polytetrafluoroethylene and modify carbide particles of metal with the intensity of the supply of mechanical energy from 0.05 to 0.5 kW/kg and a dose of from 3 to 100 kJ/kg in an environment selected from a number of: air, nitrogen, argon, vacuum pressure of 10-2to 1 ATM.



 

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