JPH0615808B2 - Vane - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vane, more specifically, a rotary pump,
The present invention relates to a vane for a seal arranged in a groove of a rotor of a rotary compressor and a vane as an apex seal for a rotary engine.

(Prior art) Since carbon materials have lubricity and can form a seal for sliding parts without lubrication, they are especially useful as vanes for rotary compressors and rotary pumps for inverters in air conditioners and refrigerators. Used in vanes that resist pollution.

Further, since the vane for sealing the high-speed rotating portion needs high strength, a carbon material impregnated with metal such as babbitt metal or aluminum is used as a base material. A specific example is an apex seal for a rotary engine, which uses a composite material in which a carbon material is impregnated with aluminum.

Also, as disclosed in Japanese Patent Publication No. 51-35648, there is proposed a rotary engine apex seal in which carbon fiber is fixedly formed with polyimide or phenol resin.

(Problems to be Solved by the Invention) However, a vane made of a conventional carbon material, a metal-impregnated carbon material, a carbon material composed of carbon fibers, or the like has insufficient wear resistance.

Further, aluminum in the carbon-aluminum composite material and the carbon base material react with each other in a high temperature portion near the sliding surface to be deteriorated,
As a result, abnormal wear may occur.

The present invention solves such problems, high strength at high temperature,
It is intended to provide a vane having excellent wear resistance.

(Means for Solving the Problems) In order to achieve the above object, the present invention is a vane formed by using a carbon material as a base material and converting a part or all of the carbon material into silicon carbide. 10% by weight in the layer
The gist of the vane is characterized in that the above carbon remains.

The carbon material as the base material of the vane is a general carbon sintered molded product,
Resin molded products, carbon fibers, carbon sheets, carbon films, etc. can be mentioned, but in the case of carbon sintered molded products, various cokes as raw materials, carbon blacks, graphite powder, etc. as fillers and pitches such as coal tar pitch and petroleum pitch. Or a synthetic resin such as a phenol resin or a furan resin as a binder or an impregnating agent, which is obtained by kneading, molding, firing and, if necessary, graphitizing. When the liquid lubrication is sufficient depending on the use conditions of the vane, a carbon material rich in carbon is used by setting the firing temperature to 1300 ° C. or lower from the viewpoint of wear resistance. On the other hand, when it is used in a state close to dry friction, it is fired and graphitized, or a carbon material having a developed graphite crystal is used as a base material by increasing the blending ratio of the raw material graphite powder.

The obtained carbon material is machined into various vane shapes.

A part or all of the vane processed in this manner is converted into silicon carbide, and particularly into β-type silicon carbide having excellent wear resistance. As the silicidation method, there are a conversion method of reacting with silicon vapor or various silicon compounds, and a method of applying a pack cementation in which an object to be processed is embedded and heat-treated with the same filler as the gas source of the conversion method. The most preferable method is a conversion method in which a silicon monoxide gas and a vane are reacted as shown in the following formula to perform processing while maintaining the shape of the vane.

SiO (g) + 2C = SiC + CO (g) This silicidation reaction proceeds by heating in the temperature range of 1300 ° C to 2300 ° C. Here, to generate silicon monoxide gas, a mixture of silicon powder and silicon dioxide powder, a mixture of silicon carbide powder and silicon dioxide powder, a mixture of carbon powder and silicon dioxide powder, or the like is used as a gas generation source. It can be performed by heating various silicon compounds to 1200 ° C to 2300 ° C.

To convert a part or all of the vane into silicon carbide, place it in the same graphite container so that it does not come into contact with the source of silicon monoxide gas, and apply silicon monoxide gas from the source of silicon monoxide gas to the surface of the vane. The silicon monoxide gas is introduced and diffused through the fine pores of the vane to carry out the silicidation reaction.

In order to convert only a desired portion of the vane into a silicon carbide layer, a graphite plate or the like other than the desired portion is applied to mask the silicon carbide layer, and the contact with the silicon monoxide gas is cut off.

When the vane and silicon monoxide are reacted to convert the vane surface layer into silicon carbide, the treatment temperature is 1300 ° C to 230 ° C.
By selecting in the range of 0 ° C., unreacted carbon can be left in the silicified layer of the vane surface layer, and various silicidation ratios, which are the proportions of silicon carbide, can be prepared according to the application.

Further, the thickness of the silicified layer on the surface of the vane can be comment-rolled by adjusting the treatment time as well as the treatment temperature. The thickness of the silicified layer is preferably 0.1 mm to 3.5 mm in view of the limit wear amount of the vane and the processing cost. In addition, the silicidation rate and the thickness of the silicified layer can be controlled by adjusting the concentration of silicon monoxide.

At least 10% by weight or more of unreacted carbon is left in the silicified layer obtained by converting the surface layer of the vane into silicon carbide. This is because the effect of imparting wear resistance peculiar to the silicon carbide component is added to the thermal conductivity and sliding characteristics peculiar to the carbon component, and a long service life is guaranteed. The residual rate of unreacted carbon can be calculated from the weight change at the time when the silicified layer is heated to 500 ° C to 800 ° C in air to oxidize the unreacted carbon to a constant weight.

The carbon material used as the vane base material may be anisotropic or isotropic depending on the difference in the manufacturing method. The anisotropic base material uses a uniaxial press machine to form the raw material powder,
A hydrostatic pressure rubber press machine is used for the isotropic substrate. In the vane of the present invention, it is preferable to use an isotropic substrate having various properties such as mechanical properties and thermal properties which are substantially constant in any direction and which has particularly high strength. This is because the material can be taken efficiently, the strength of the vane is increased, and the coefficient of thermal expansion of the isotropic substrate is constant in each direction, so even if a two-layer structure in which a part is converted to silicon carbide is used, an anisotropic substrate can be used. This is because the design becomes simple because no local internal stress is generated.

When the carbon material serving as the base material of the vane is carbon fiber, a part or all of the carbon fiber compact formed into the vane shape is converted into silicon carbide as in the case of the carbon sintered compact. In addition to this, a part or all of the carbon fibers may be converted into silicon carbide in advance by the above-mentioned method, and the carbon fibers may be used to form a vane to form a constant shape.

The internal structure of the vane based on the carbon material thus obtained has the same structure as the fine pores of the carbon material before the conversion to silicon carbide, and it does not change even if it is converted to silicon carbide by the silicidation reaction. Is known from the reaction morphology and from the actual measurement results. Therefore, if necessary, a metal such as babbitt metal or aluminum can be impregnated through the fine pores by a conventional method to improve the strength.

(Operation of the Invention) In the present invention, silicon monoxide gas is permeated and diffused into the surface layer of a vane having a carbon material as a base material, reacts with the vane itself to be converted into silicon carbide, and unreacted carbon is contained in the silicified layer. Is characterized in that 10% by weight or more remains, and various substances are deposited on the carbon material by the CVD method, the PVD method, or a method such as plating, thermal spraying or coating. It is fundamentally different from the one that became.

In other words, CVD method, PVD method, plating, thermal spraying,
The surface of the carbon substrate obtained by coating etc. is bonded to various deposited film substances and the surface of the carbon substrate only by physical adhesion such as van der Waals force. When a vane is used, repeated use at high temperature and high pressure causes the deposited coating material to peel due to a difference in thermal expansion, shear stress, etc., resulting in early deterioration of wear resistance.

However, the surface layer of the vane of the present invention is mainly composed of silicon carbide, which is the most stable material and is not chemically corroded and is excellent in oxidation resistance and wear resistance, and the surface layer of the vane itself reacts with silicon monoxide. Since it has changed to silicon carbide, the boundary has a completely continuous structure, and the silicified layer does not peel off due to repeated use under high temperature and high pressure, and at the same time, it has the effect of imparting wear resistance specific to the silicon carbide component. Wear resistance is secured over a long period of time due to the sliding characteristics unique to the carbon component.

On the other hand, the deposited film obtained by the CVD method, the PVD method, the plating, the thermal spraying, the coating or the like has very few fine pores, so that the subsequent metal impregnation, which is performed as necessary, cannot be sufficiently performed.

It is also possible to carry out the metal impregnation before the surface treatment step such as the CVD method or the PVD method, but the treatment temperature in the subsequent surface treatment step often falls within the range of 700 ° C to 1300 ° C. Depending on the treatment temperature, the metal may elute, a chemical reaction may occur between the carbon base material and the impregnated metal, and the carbon base material may be altered, or in some cases cracks may form.

However, since the internal structure of the vane of the present invention has the same structure as the fine pores of the carbon material before being converted into silicon carbide, even though the surface layer has a structure containing silicon carbide as a main component, The metal impregnation can be sufficiently performed by a conventional method.

Further, since silicon carbide is a substance that is extremely stable against various metals, especially aluminum, it prevents alteration and abnormal wear near the sliding surface of the vane.

Next, the present invention will be specifically described with reference to examples.

(Example) Example 1 Coke and artificial graphite powder as a filler, coal tar pitch as a binder, these compounds were heated and kneaded to obtain a kneaded product, which was then crushed and then molded with a rubber press at 1000 ° C. Fired, Shore hardness 90, Bending strength 11
An isotropic carbon material of 00 kg / cm ² was obtained.

A vane machined from this carbon material into the shape of an apex seal for a rotary engine as shown in FIG.
(1) was prepared.

This vane (1) was placed in the same graphite container so as not to come into contact with 1.5 kg of a mixture of silicon powder and silicon dioxide powder (molar ratio 1: 1), sealed and heated at 1800 ° C. for 120 minutes at this temperature. Holding, the surface layer was converted to silicon carbide.

As a result of this treatment, as shown in the sectional view of FIG.
A vane (1) having a layer (2) in which the surface layer of (1) had a thickness of about 2.6 mm and which was converted to β-type carbon silicon containing 15% by weight of unreacted carbon was prepared.

As shown in the schematic diagram of FIG. 3, the layer (2) converted to silicon carbide has a portion (4) converted to silicon carbide and an unreacted carbon portion (5) at a thickness of about 2.6 mm from the surface and It consists of fine pores (6).

The vane made of the carbon material obtained by converting the surface layer thus obtained into silicon carbide had a Shore hardness of 95 and a bending strength of 1870 kg / cm ² .

Next, aluminum was impregnated through the fine pores of the vane to obtain a final product vane having a structure in which the fine pores were filled with aluminum (7) as shown in the schematic view of FIG. The final product has a Shore hardness of 95 and a bending strength of 310.
It was 0 kg / cm ² .

This vane was placed in an air atmosphere at 600 ° C., and the oxidative consumption rate after 100 hours was measured. As a result, it was about 1/12 of the oxidative consumption rate of the conventional vane whose surface layer was not converted to silicon carbide.
Met.

Further, in the conventional vane in which the surface layer was not converted to silicon carbide, the carbon material and aluminum reacted and deteriorated, and a hair crack was formed on a part of the surface, whereas an abnormality was recognized in the vane of the present invention. There wasn't.

The wear rate was measured by contacting the vane with a rotating body of stainless steel at a pressure of 588 N. As a result, the wear rate was about 1/3 of that of a conventional vane whose surface layer was not converted to silicon carbide.
Met.

Example 2 Using the same isotropic carbon material as in Example 1, a vane (1) was machined into the same shape of an apex seal for a rotary engine.

This vane was charged into a graphite container together with 1 kg of a mixed powder of carbon powder and silicon dioxide powder (molar ratio 3: 1),
Heat to 00 ° C. and hold at this temperature for 120 minutes.

As a result of this treatment, a vane having a thickness of about 3.3 mm and converted into β-type silicon carbide containing 22% by weight of unreacted carbon was obtained.

Next, this vane was impregnated with aluminum in the same manner as in Example 1 to obtain a Shore hardness of 90 and a bending strength of 3210 kg / c.
A final product vane of m ² was obtained.

This vane was placed in an air atmosphere at 600 ° C., and the oxidation consumption rate after 100 hours was measured. As a result, it was about 1/15 of the oxidation consumption rate of a conventional vane whose surface layer was not converted to silicon carbide.
Met.

Further, in the conventional vane in which the surface layer was not converted to silicon carbide, the carbon material and aluminum reacted and deteriorated, and hair cracks were formed on a part of the surface, whereas no abnormality was observed in the vane of the present invention. It was

The wear rate was measured by contacting this vane with a rotating body made of stainless steel at a pressure of 588 N, and as a result, the wear rate was about 1/4 of that of a conventional vane whose surface layer was not converted to silicon carbide.
Met.

Example 3 The same isotropic carbon material as used in Example 1 was machined into the shape of a vane of a rotary compressor used for an air conditioner for heating and cooling,
A part of the surface layer was converted to silicon carbide in the same manner as in Example 1 to impregnate aluminum and prepare a final product.

As a result of incorporating this vane into a rotary compressor and measuring the amount of wear, it was about 1/4 of the amount of wear of a conventional vane in which the surface layer was not converted to silicon carbide.

(Effect of the Invention) As described above, the vane of the present invention is formed by converting a part or all of the vane into silicon carbide, and 10% by weight or more of carbon remains in the silicified layer converted to silicon carbide. Because
The wear resistance of the vane is significantly improved by adding the heat conductivity and sliding characteristics peculiar to the carbon component to the effect of giving the wear resistance peculiar to silicon carbide.

In addition, since the layer of this vane converted to silicon carbide uses the carbon base material itself as the carbon component of silicon carbide, it has a continuous structure at the boundary between the carbon base material and the silicon carbide layer, resulting in peeling and powder falling. It can be used stably without any troubles.

On the other hand, in the case of this vane, the reaction between the aluminum and the carbon material, which occurs at a high temperature portion such as the sliding surface of the vane, and the resulting abnormal wear are completely eliminated by taking the composite structure of aluminum and silicon carbide, At the same time, the oxidation resistance is improved.

Further, since this vane is reinforced by silicon carbide, it is possible to obtain a vane having higher strength than the conventional vane.

Further, in this vane, a metal such as Babbitt metal or aluminum can be impregnated through the fine pores in the substrate, so that the strength thereof can be remarkably improved as compared with the non-impregnated one.

[Brief description of drawings]

FIG. 1 is a perspective view of a vane as an apex seal for a rotary engine according to the present invention, and FIG. 2 is A- in FIG.
FIG. 3 is an enlarged schematic view of an A portion of FIG. 2 before metal impregnation, and FIG. 4 is an enlarged schematic view of an A portion of FIG. 2 after impregnation with aluminum. DESCRIPTION OF SYMBOLS 1 ... Vane, 2 ... Layer converted to β silicon carbide containing unreacted carbon, 3 ... Carbon substrate, 4 ... Part converted to β-type silicon carbide, 5 ... Unreacted carbon Part, 6 ... Fine pores, 7 ... Aluminum impregnated into fine pores.

Claims (2)

[Claims] 1. A vane comprising a carbon material as a base material, a part or all of which is converted to silicon carbide, wherein 10% by weight or more of carbon remains in the silicified layer converted to silicon carbide. A vane characterized by. 2. The vane according to claim 1, wherein the base material is impregnated with a metal.