JPS6138236B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a carbonaceous sliding material with excellent load carrying capacity and wear resistance. The general manufacturing method for carbonaceous sliding materials is as follows. A binding material such as tar or pitch is added to a carbonaceous material such as coke, graphite, or carbon black, and the mixture is brought together at a temperature above the melting temperature of the binding material. This mixture is either extruded as it is, or is cooled, pulverized and pressure molded, and then calcined in a non-oxidizing atmosphere at a temperature of about 800 to 1200°C. If necessary, this fired product is treated at 2000 to 3000°C to graphitize it. Additionally, fired or graphitized products are impregnated with tar, pitch, or resin, and then fired or graphitized. Furthermore, in order to improve the strength of the carbonaceous sliding material, improve airtightness, and make it impermeable, impregnation with tar, pitch, and various resins such as phenol resin and furan resin is performed. The carbonaceous sliding material obtained in this way has good lubricity and a small coefficient of friction.
Taking advantage of its features such as non-seizing and good chemical resistance, it is used in a wide variety of applications, including shaft sealing parts, bearings, packing, blower blades, and vacuum pump blades. However, in recent years, usage conditions have become increasingly severe, and there are now fields in which carbonaceous sliding materials manufactured by the conventional method as described above cannot be used due to insufficient load resistance, heat resistance, abrasion resistance, etc. Examples include shaft sealing materials for stirrers for autoclaves under high temperature and high pressure, sealing materials for high temperature and high pressure fluid transport pumps, shaft sealing materials for nuclear equipment that require high reliability, and vane materials for high speed vane pumps. The object of the present invention is to obtain a high-performance carbonaceous sliding material that can be used in the above-mentioned applications where conventional carbonaceous sliding materials cannot withstand use. Conventional technology has low coefficient of friction,
Although it was evaluated from the viewpoint of stability of friction coefficient,
In the present invention, the effects of the present invention were confirmed by evaluating the characteristics from practical aspects such as load resistance, abrasion resistance, and surface roughness of the sliding material. A few examples of recent harsher usage conditions and required characteristics are as follows. In other words, as an example of harshness, PV = 1500 to 2000 (Kg/cm ² , m/sec) as a mechanical seal material for petrochemical and nuclear equipment.
There are also those with an operating temperature of 300 to 400℃. In addition, maintenance and inspection cycles are required to be extended, and for industrial use, it is required to last two to three years instead of the conventional one year, and it is expected to prevent a decrease in the operating rate due to suspension of operations for inspection. Furthermore, maintenance-free products are required for civilian use, such as pump sealing materials for central cooling and heating in general households. Therefore, improving the wear resistance of sliding materials is an urgent issue. The present invention uses a carbonaceous material, a rare earth compound whose main component is a fluoride, a silicate, a phosphate, or a carbonate as a binder, one type of rare earth mineral, or a mixture thereof;
The present invention relates to a carbonaceous sliding material containing one type or a mixture of two or more types of polishing agents. As mentioned above, the present invention has been made to improve load resistance, heat resistance, and abrasion resistance. A carbonaceous material prepared by a conventional method using a rare earth compound containing fluoride, silicate, phosphate or carbonate as a main component, one type of rare earth mineral or a mixture thereof and a mixture of one or more types of polishing agent. By adding it to the above, we were able to achieve the desired purpose of improving load carrying capacity, abrasion resistance, and heat resistance superior to conventional products. Because rare earths have similar properties, it is difficult and expensive to separate them in pure form, so the rare earths mentioned here have cerium as their main component, and other rare earths such as lanthanum, yttrium, praseodymium, neodymium, and gadolinium. Including single substances and mixtures thereof. Examples of materials used include industrial grade cerium fluoride of varying purity, rare earth fluorides, silicates, phosphates, and carbonate minerals such as cerite, monazite, melanocerite, cariocerite, mosandrite, and bastnaesite. As the polishing agent, alumina, silica stone, tripoli, calcined dolomite, emery, chromium oxide, red iron oxide, silicon carbide, etc. can be used. The method of using the rare earth compound and polishing agent according to the present invention is to mix the rare earth compound and polishing agent in a predetermined amount with a carbonaceous material such as graphite, coke, carbon black, etc. in a conventional manner. After that, it is melted and mixed with binding materials such as tar and pitch at a temperature of 100 to 300 degrees Celsius, and after cooling, it is pulverized and molded. Also, if only carbonaceous materials are mixed,
A rare earth compound and a polishing agent are added to the pulverized material later. The amount of rare earth compound and polishing agent added is preferably 2 to 20% by weight as ash content in the fired product.
However, it is more preferably 3 to 10% by weight. If it is too small, the addition has no effect, and if it is too large, the wear resistance deteriorates. The particle shape of the additive is preferably spherical with rounded edges as much as possible. Therefore, it is desirable that the additive be processed by a ball mill or the like after being finely pulverized. The particle size of the additive is less than 50 microns, preferably less than a few microns. The blending ratio of the rare earth compound and polishing agent can be changed depending on the required wear resistance, heat resistance, load resistance, and the type of mating shaft material, sealing material, etc. used. The present invention will be explained below with reference to Examples. Example 1 To 100 parts by weight of the carbonaceous material shown in Formulation Example 1 in Table 1, 50 parts by weight of coal tar pitch, 20 parts by weight of coal tar, the rare earth compound and polishing agent 12 shown in Example 1 in Table 2. Parts by weight were added and mixed.
As for the mixing method, first, the carbonaceous materials shown in Table 1 are weighed and mixed in advance. Next, the rare earth compound and polishing agent shown in Table 2 are weighed and mixed separately from the carbonaceous material shown in Table 1 (hereinafter this will be referred to as the blended polishing agent). The blended polishing agent is added to the carbonaceous material premixed as shown above and mixed again. Next, transfer these mixtures to a mixing machine and raise the temperature to 120°C while stirring. Separately, coal tar pitch and coal tar were mixed in the above proportions and preheated and melted at about 150℃.
Transfer to a Japanese rice cooker and combine with the above mixture.
= Summarization was carried out at 200°C for 4 hours. Thereafter, the hydrate was taken out, cooled, and pulverized to 325 meshes, and the pulverized product was further placed in a mold and pressure-molded at a pressure of 1500 Kg/cm ² . This molded article was fired using the general firing method described above. The firing rate was 2°C/hour, the maximum temperature was 900°C, and the holding time was 1 hour. This fired product was placed in a vacuum pot and degassed at 250° C. and under a vacuum of 1 mmHg for 2 hours, and then molten pitch was injected and impregnated under pressure at 10 atm for 5 hours. Remove from the pot when hot,
The adhering pitch was scraped off and cooled. The fired product impregnated with pitch was fired again in the kiln during firing. This fired product was impregnated with furan resin under vacuum pressure, and after being sufficiently impregnated with the resin, it was cured to produce an impermeable carbonaceous sliding material. Example 2 An impermeable carbonaceous sliding material was prepared in the same manner as in Example 1 except that the blending ratios of the carbonaceous material, rare earth compound, and polishing agent were as shown in Table 1 and Table 2. manufactured the material. Example 3 An impermeable carbonaceous sliding material was prepared in the same manner as in Example 1, except that the blending ratios of the carbonaceous material, rare earth compound, and polishing agent were as shown in Compounding Example 3 in Tables 1 and 2. manufactured the material. Comparative Example An impermeable carbonaceous sliding material was produced in the same manner as in Example 1 except that no abrasive agent was added at the blending ratios shown in Examples 1 to 3. Although a few examples of the formulation and manufacturing method of the carbonaceous sliding material in the embodiments described above have been described in the present invention, it goes without saying that various formulations and manufacturing methods other than these are possible.

【table】

[Table] A comparison of the characteristics of the carbonaceous sliding material of the present invention and the conventional carbonaceous sliding material is shown below. 100mm of carbonaceous sliding material manufactured by the method shown in Examples and Comparative Examples
It was assembled into a mechanical seal with a shaft diameter of (φ). The mating material used was a cemented carbide made of tungsten carbide and a nickel binder that was sprayed onto SUS304 to a thickness of approximately 1 mm. Rotation speed: 200 rotations/min, surface pressure: 20Kg/cm ² , sealing liquid: ethylene glycol, test time: 100 hours,
Test temperature: A mechanical seal test was conducted at 60°C. The test results are shown in Table 3.

[Table] From this result, it is clear that the wear resistance was improved by the present invention. The test conditions this time were relatively low, with a PV value of about 20 (Kg/cm ² m/sec), but ethylene glycol had a low film-forming ability, and the carbide used was a thermal spray type, so the binder This makes it more susceptible to etching due to sliding pyrolysis products of ethylene glycol.
The conditions are considered to be harsh, as the carbide sliding surfaces tend to become rough. For this reason, the conventionally used carbon sliding materials for mechanical seals cannot be used due to the large amount of wear, so it is necessary to develop a new wear-resistant carbon sliding material, and as a result of various studies, we have arrived at the present invention. The details of the mechanism of action of various additives according to the present invention on improving wear resistance are unknown. The intended effect is as follows. Rare earth fluoride decomposes during high-temperature sliding and becomes rare earth oxide, which helps prevent oxidation of ethylene glycol. The added polishing agent smooths the etched portion of the sliding surface, thereby preventing wear of the carbon material caused by the carbide, preventing destruction of the sealing liquid film, and improving lubricity. From the actual machine test results shown in Table 3, we believe that the inventor's intention has been experimentally proven. Next, using a Matsubara friction and wear tester (manufactured by Toyo Baldwin KK), the PV limit value, which is one of the indicators of load resistance, was measured. Sliding material test piece size 20mm
(φ)×25.6mm(φ) (sliding area 2cm ² ), mating material FC
-25 (4 types of gray cast iron products), a peripheral speed of 1000 revolutions/min (1.34 m/sec), a load of 25 kg/cm in ² steps held for 10 minutes in the atmosphere, and the PV limit was measured. . The results are shown in Table 4. This result shows that the sliding material of the present invention has an improved PV limit compared to the conventional carbonaceous sliding material.

【table】

Claims (1)

[Claims] 1 Carbonaceous material, rare earth compound whose main component is fluoride, silicate, phosphate or carbonate as a binder,
A carbonaceous sliding material made by adding one kind of rare earth mineral or a mixture thereof and one kind of abrasive agent or a mixture of two or more kinds.