KR20050100974A - Composition for treating surface of swash plate and method for treating surface on its by the composition - Google Patents

Abstract

The present invention relates to a swash plate surface treatment composition and a surface treatment method using the same, specifically, a swash plate surface treatment composition including Bi and Sn, and a pre-treatment of the swash plate (step 1); Underplating the pretreated swash plate (step 2); And a step (step 3) of forming a solid lubricating layer using the surface treatment composition on the under plated swash plate.

Swash plate surface treatment composition of the present invention is composed of Sn and Bi has a lower melting point than when using only conventional Sn can increase the spreadability during high-speed lubrication, thereby further improving the lubricating properties. In addition, it is possible to improve the lubricity and wear resistance compared to other conventional compositions.

In addition, through the surface treatment method of the present invention it is possible to perform the surface treatment of the swash plate having good adhesion and high reliability and durability.

Description

COMPOSITION FOR TREATING SURFACE OF SWASH PLATE AND METHOD FOR TREATING SURFACE ON ITS BY THE COMPOSITION}

The present invention relates to a swash plate surface treatment composition and a surface treatment method using the same.

Conventionally, a compressor used in an automotive air conditioner has a function of sucking the vaporized heat exchange medium in the evaporator, compressing the sucked heat exchange medium, and pumping the compressed heat exchange medium to continuously circulate the refrigerant. According to the driving method, there are various types such as a swash plate type, a scroll type, a rotary type, and a wobble plate type.

The double swash plate is a part that contacts the piston and a shoe that is slidably supported to reciprocate the piston to continuously compress the refrigerant, and has a main function of transferring generated energy. Specifically, a shoe is installed at the contact portion of the swash plate and the piston to reduce frictional force due to the contact and to smooth the flow of the swash plate, whereby the swash plate and the shoe make sliding contact. However, a swash plate made of an aluminum alloy and a shoe made of an iron alloy or a copper alloy generate considerable heat of friction by high-speed rotation when the air conditioner is operated. Due to the high temperature generated, if the swash plate and shoe that are in sliding contact are not formed with the proper lubricating film, the energy transfer efficiency may be reduced due to wear between the two parts, and in some cases, even sintering may occur. The role of the lubricating membrane to prevent wear during wear will be very important. Therefore, many efforts have been made to find a better lubrication condition, one of which is to provide a lubrication layer by surface treatment of the swash plate.

Conventionally, a thermal lubrication coating of a copper (Cu) -based alloy on the surface of a swash plate forms a solid lubrication film, thereby improving lubrication characteristics. However, since the coating film of the copper-based alloy formed by the spray coating has a limit in maintaining adhesion with the material of the swash plate, the reliability is lowered. In particular, there is a problem that the Cu coating film is separated from the surface of the swash plate due to the lack of adhesion between the swash plate and the Cu-based coating film under high speed operation of the compressor.In the case of thermal spray coating, small metal powder is laminated on the surface of the swash plate. Their particles fall and cause friction between parts.

Meanwhile, an example of a composition for solid lubrication is disclosed in US Pat. No. 4,473,481. The disclosed solid lubricating composition prevents breakage of the metal surface subjected to sliding motion, and includes 60 to 80% by weight of molybdenum disulfide or molybdenum disulfide and graphite and antimony, iron, zinc or gold particles as an additive for imparting heat stability and preventing oxidation. It is a lubricant composition containing 10 to 30% by weight of any one component and any one of an epoxy-ester resin, an acrylic resin and a urea resin as an organic binder.

In addition, Japanese Patent Laid-Open No. Hei 4-26777 discloses a method of forming a film having excellent heat abrasion resistance and wet resistance to titanium or a titanium alloy. In this patent, before applying a solid lubricating film on the surface of the material, as a pretreatment, the surface of the material is heated to 500 ° C. in a vacuum atmosphere and chemically activated to make the material surface porous. Electroplating of the material improves heat resistance and wear resistance.

However, as described above, the solid lubricant film on the coating material using the organic or inorganic binder is difficult to control the coating film thickness, difficulty in controlling the ratio of the solid lubricant and the binder, and due to the problem of partial film thickness unevenness depending on the shape of the part. Application to precision parts has considerable difficulty. In addition, when there are many resins in a solid lubricating film, lubrication property will worsen, and when there are many pigments which are lubricants, lubrication property will improve but it will be easily abraded and life will be shortened.

An object of the present invention is to solve the problems of the conventional swash plate surface treatment, to provide a composition for swash plate surface treatment and a surface treatment method using the same significantly improved the lubricity deterioration due to frictional heat.

In order to achieve the above object, the present invention provides a swash plate surface treatment composition containing Bi and Sn.

The present invention also provides a swash plate surface treatment method using the composition.

Hereinafter, the present invention will be described in detail.

The present invention provides a swash plate surface treatment composition containing Bi and Sn.

Sn (Tin) is used as a conventional swash plate surface lubricant, melting point due to high speed lubrication is 232 ℃. In the present invention, as a composition containing such Sn and Bi (Bismuth), when the surface treatment using the composition, the melting point due to high-speed lubrication can lower the melting point to 225 ℃, due to this phenomenon increases the spreadability during high-speed lubrication Lubrication characteristics can be improved. Bi preferably comprises 0.2 to 20% by weight. If Bi is less than the above range, sufficient spreading effect cannot be obtained, so that the lubrication property deteriorates. If the Bi exceeds the above range, the lubrication property is improved, but the wear life is easily shortened to shorten the life.

In addition, the composition of the present invention further comprises polytetrafluoroethylene (PTFE) to reduce frictional resistance and further increase lubricity. Since polytetrafluoroethylene has excellent lubricity and is a material applied as a solid lubrication film alone, or because of its low resistance to heat and strength, polytetrafluoroethylene is incorporated into the composition as a fine particle in the Sn-Bi alloy plating rather than being used alone. Overcome and maximize the lubricity of Sn-Bi. The smaller the particle size is, the more preferable. Specifically, one having a particle size of 1 μm or less is used. When the particle size exceeds the above range, not only the adhesion of the Sn-Bi plating layer formed after the surface treatment is degraded, but also such particles are separated from the surface to cause friction between parts. The polytetrafluoroethylene particles are contained in an amount of 0.5 to 8% by weight based on the composition in order to improve the properties of the additives. If it is less than the above range can not obtain the effect of reducing the friction resistance and increase the lubricity, if exceeding the above range, the lubrication properties are improved but wear is easily abrasion shortens the life.

In addition, the present invention provides a swash plate surface treatment method using the surface treatment composition of the present invention.

Specifically, pre-processing the swash plate (step 1);

Underplating the pretreated swash plate (step 2); And

It provides a surface treatment method of the swash plate comprising the step (step 3) of forming a solid lubricating layer using the composition for the swash plate surface treatment on the base plated swash plate.

In step 1 the swash plate is pretreated.

Since the swash plate cast from the aluminum alloy is attached with fine foreign matters generated in the manufacturing process, it is removed by using ultrasonic waves, and afterwards, alkali degreasing is performed to completely remove foreign matters from the surface. The ultrasonic degreasing and alkali degreasing are carried out by a method conventionally used.

In step 2, the pretreated swash plate is plated.

The underplating step is a process of sinter plating the pretreated swash plate, and is specifically performed in the order of the first ginkgo treatment, jinkate peeling, the second gongkat treatment, the cyanide copper strike plating.

The gating process is performed before the cyanide copper strike plating is performed on the surface of the pretreated swash plate. Aluminum, the material of the swash plate, is an active metal and its surface is always covered with an oxide film. For this reason, plating directly on aluminum is difficult, and in general, it is to substitute and deposit another metal, and to perform plating on the substituted and deposited metal film. Aluminum is an active metal and is easily substituted and precipitated in a solution containing a metal salt, so that the zinc coating is performed to improve adhesion. The gating process can be easily carried out by those skilled in the art.

In the present invention, the gating process is performed in two stages. After the first gating process, the gating formed on the surface of the aluminum alloy is almost dissolved by immersion in nitric acid. However, the aluminum surface is left in the alloy substitution component is electrochemically more precious than the aluminum material, the surface is scattered with a myriad of substances that act as a nucleus of the substitution reaction. When the aluminum alloy swash plate is secondarily deposited in the quenching liquid, this electrochemical potential difference forms a substitution reaction in which the amount of the substitution metal instantly covers the entire surface. By performing the scouring treatment twice in this manner, it is possible to reduce the disadvantages such as segregation of the aluminum alloy component and to obtain good adhesion.

After completion of the second jincate process, the cyanide copper strike plating is performed.

In the present invention, the cyanide copper strike plating is carried out to improve the adhesion between the zinc and Sn-Bi alloy plating and the buffering effect. The plating is performed at a pH of 12 to 13 and a temperature of 45 to 60 ° C.

In step 3, a solid lubrication layer is formed using the composition of the present invention. Specifically, the Sn-Bi solid lubricating layer is formed using the composition of the present invention.

The plating is made by an electrical method. At this time, examples of the composition of the plating liquid are Sn 20-50 g / l, Bi 3-8 g / l. It consists of SNB 11 150-250g / l, SNB 22 20-80g / l, SNB 14 8-15g / l. Available temperature range is 35 ~ 50 ℃ and optimum condition is 40 ℃. The range of cathode current density is 10-30 A / dm 2 and the optimum condition is 15 A / dm 2.

In the present invention, the method can prevent the Sn-Pest phenomenon by maximizing the lubricity of the plating layer by suppressing the generation of α-Sn on the plating surface, which is easy to occur in conventional Sn plating.

Hereinafter, the present invention will be described in detail by way of examples.

However, the following examples are merely to illustrate the present invention is not limited to the contents of the present invention.

Example 1 Surface Treatment of Swash Plate

The swash plate was subjected to ultrasonic degreasing and alkali degreasing to completely remove foreign substances on the surface. The treated swash plate was dipped in the quenching liquid to perform the first jinating treatment, and then immersed in nitric acid to dissolve the jincate formed on the surface of the aluminum alloy. Subsequently, the second zinc gating treatment was carried out by dipping again in the same solution as the first zinc liquid. The secondary zincated treated swash plate was plated with copper cyanide at a temperature of pH 12.5 and 50 ° C., and then plated by Sn-Bi plating solution (Bi 3% by weight) by electrical method, followed by washing and drying.

<Example 2>

The same procedure as in Example 1 was performed except that 15% polytetrafluoroethylene (PTFE) having 0.8 μm particle size was added to the Sn-Bi (Bi 3%) plating solution.

Comparative Example 1

The surface treatment was performed in the same manner as in Example 1, except that the Sn plating solution was used instead of the Sn-Bi plating solution.

Comparative Example 2

The surface treatment was performed in the same manner as in Example 1, except that Sn-Ag (Ag 3.5 wt%) plating solution was used instead of the Sn-Bi plating solution.

Comparative Example 3

The surface treatment was performed in the same manner as in Example 1 except that Sn-Cu (Cu 0.75 wt%) plating solution was used instead of the Sn-Bi plating solution.

Experimental Example 1

The swash plates produced in the above examples and comparative examples were subjected to limit lubrication test, load bearing effect test and abrasion test, respectively.

Specifically, the lubrication test measured the time until the plating layer of the swash plate is broken and sintering occurs due to the rotational motion of the high load.

The load bearing effect test gradually measured the load value from the lower load to the higher load until the plating layer was broken.

The abrasion test was performed for a certain period of time with a proper load to measure the weight of the swash plate reduced by wear.

The experimental results are shown in Table 1.

Kinds Example Comparative Example One 2 One 2 3 Marginal lubrication effect Crossing time (seconds) 612 950 540 900 891 Load bearing effect Cross load (kg) 902 655 885 605 598 Abrasion Test Effect Weight loss (mg) 0.51 0.2 0.53 0.52 0.53

As shown in Table 1, when the Sn-Bi surface treatment, it can be seen that the lubricity and wear resistance is superior to the Sn surface treatment, in particular, when PTFE is added to the plating solution, the lubricity and wear resistance was the most excellent.

Sn-Ag surface treatment showed good lubricity, but it was inferior in load bearing effect and abrasion resistance. Sn-Cu surface treatment also secured some superiority in lubricity, but the load bearing effect was the lowest, and the weight loss was also high in the wear test effect.

As described above, the swash plate surface treatment composition of the present invention is composed of Sn and Bi has a lower melting point than when using conventional Sn only can increase the spreadability during high-speed lubrication, thereby further improving lubricity. . In addition, it is possible to improve the lubricity and wear resistance compared to other conventional compositions.

In addition, through the surface treatment method of the present invention it is possible to perform the surface treatment of the swash plate having good adhesion and high reliability and durability.

1 is a perspective view showing a swash plate having a Sn-Bi alloy layer of the present invention.

Claims (8)

Swash plate surface treatment composition containing Bi and Sn. The composition for swash plate surface treatment according to claim 1, wherein the composition is made from 0.2 to 20 wt% of Bi and remainder of Sn. The composition of claim 1 or 2, further comprising 0.5 to 8% by weight of polytetrafluoroethylene. Pretreating the swash plate (step 1); Underplating the pretreated swash plate (step 2); And And a step (step 3) of forming a solid lubricating layer using the swash plate surface treatment composition on the under plated swash plate. 5. The surface treatment method according to claim 4, wherein the pretreatment step is performed sequentially by supersonic degreasing and alkali degreasing. 5. The surface treatment method according to claim 4, wherein the base plating step is performed in the order of the first gating process, the gating method, the second gating process and the cyanide copper strike plating. 7. The surface treatment method according to claim 6, wherein the cyanide copper strike plating is performed at a pH of 12 to 13 and a temperature of 45 to 60 캜. The surface treatment method according to claim 4, wherein the solid lubrication layer is formed at a temperature of 35 to 50 ° C and a cathode current density of 10 to 30 A / dm ² .