JPS6250435B2 - - Google Patents

Description

[Detailed description of the invention]

Recently, ceramic materials with excellent corrosion and wear resistance have been widely used as seal rings for mechanical seals. Conventional methods for bonding a ceramic seal ring to a base metal include sintering, brazing, and using soft solder materials. The sintering method has the disadvantage that the part becomes very hot, approaching the melting point of at least one of the materials of the part, and the use of brazing techniques requires an expensive metallized layer on the facing or surface of the ceramic, which is not necessary for brazing. High temperatures are often associated with the disadvantage that stress caused by the brazing process can cause cracks in the ceramic material. In addition, in this process, the ceramic ring is sintered and then bonded to the base metal of the seal ring, which is a complicated process.Moreover, when brazing or gluing a thin ceramic seal ring, it is difficult to crack the ceramic material. Sometimes this occurred. Additionally, due to the use of brazing filler metal or adhesive, corrosion resistance was poor. On the other hand, as a method for joining ceramics to a base metal, in addition to the above-mentioned method, methods are often used, such as mechanically processing the joining surfaces and intertwining them to join them, or joining these two objects by cutting threads. However, in this case, machining of the ceramic member is extremely difficult, and minute cracks generated during machining often cause damage to the ceramic, resulting in a high price. In the present invention, a seal ring of a mechanical seal obtained by sintering B ₄ C powder whose surface is coated with ethyl silicate on a carbon base material by a hot pressing method and simultaneously adhering to the base material, and its manufacture. The sintering temperature is preferably 1900 to 1950°C and the sintering pressure is 100 to 200 kg/cm ² . The structural formula of ethyl silicate is that in addition to the monomers shown below, 4 to 6 of the above monomers are directly present. It has a low condensate structure in which several molecules are condensed in a chain or branched form. This ethyl silicate is usually a colorless and transparent oily liquid. A series of experiments that led to the development of the present invention and their results will be described below. [Experiment 1] B ₄ C powder: Ethyl silicate diluted with water and alcohol and diluted with dilute hydrochloric acid as a catalyst was applied to the surface of B ₄ C powder particles of 350 mesh or less in terms of silicon content (B ₄ C + Si) as shown in Table 1. Powder blended to give each amount shown. Base material: Carbon hot press Sintering bonding: Sintering bonding was carried out under the conditions of sintering bonding temperature: 1950°C, sintering bonding time: 60 minutes, and pressure: 200 kg/cm ² . Next, each B ₄ C sintered body was ground with a #200 diamond grindstone, and the surface condition and hardness of the sintered body were measured, and the adhesion state between B ₄ C and carbon was observed. The result is also the same as the first one.
Shown in the table.

【table】

[Experiment 2]

B ₄ C powder: B ₄ C powder of 350 mesh or less and Si and SiC powder of 350 mesh or less are blended as shown in Table 2. Powder base material: Carbon hot press Sintering bonding: Sintering bonding temperature 1950℃ Sintering and bonding was carried out under conditions of a sintering bonding time of 60 minutes and a pressure of 200 kg/cm ² . Next, each B ₄ C sintered body was ground with a #200 diamond grindstone, and the surface condition and hardness of the sintered body were measured, and the adhesion state between B ₄ C and carbon was observed. The result is also shown in the second
Shown in the table.

[Experiment 3]

B ₄ C powder of 350 mesh or less was used, and the powder was mixed as shown in Table 1 and Table 2.
Kg/ ^cm2 50×50×5.5 under the condition of 60 minutes sintering time
(mm) of the sintered body was obtained. Next, each sintered body was cut and ground with a diamond grindstone to form four 5×8 pieces.
A test piece of ×24 (mm) was prepared, and its specific gravity, hardness, and bending strength were measured. The measured values obtained are shown in Table 3.

[Table] From the above experimental results, the following can be seen. That is, when B ₄ C powder was coated with ethyl silicate and sintered on a carbon ring base material by hot pressing, and at the same time adhered to the base material, B ₄ The surface condition of the C sintered body and the adhesion to the base material are excellent. From Tables 1 and 3, the reason why the adhesion to the carbon base material and the sinterability of B ₄ C are excellent is that the amount of ethyl silicate added must be at least 2% by weight as Si content. I understand. If the amount is too high, reaching 30% by weight, the bending strength will drop significantly, and if the adhesion state also reaches 30% by weight, the reaction between Si and C in ethyl silicate will be intense, and some voids will be seen in the C base material bonding layer. . In addition, sample No. 5 manufactured by the method of the present application
The adhesive layer between B ₄ C and C was examined by X-ray analysis. X
Line diffraction patterns are shown in FIGS. 1 to 3. Figure 1
In the B ₄ C sintered layer, most of the added ethyl silicate becomes β-SiC and is uniformly mixed with B ₄ C. At the bonded part between B ₄ C and C in Figure 2,
B ₄ C and β-SiC are the main components, with a trace amount of C visible. In the C layer shown in FIG. 3, C and β-SiC are the main components. i.e. B ₄ C by the addition of ethyl silicate
sintering is promoted and can be sintered at low temperatures. In addition, Si in ethyl silicate partially reacts as a C matrix and becomes β
-SiC, and it can be seen that the bond between B ₄ C-β-SiC-C is strong. Also, from Experiment 2 conducted for comparison, it can be seen that the product produced by the method of the present invention is superior. As a hot press manufacturing method for a mechanical seal ring, a specific example of the manufacturing method will be shown below. As shown in FIG. B ₄ C whose surface was coated with ethyl silicate in the groove
Powder 2 is filled, and this B ₄ C powder is pressed and heated at the same time to sinter the B ₄ C and adhere it to the base material of the carbon seal ring base. As shown in Fig. 5, the inner and outer peripheries of the concave groove are formed. There is a method of manufacturing a mechanical seal ring by removing carbon on surfaces 3 and 4 (dotted shaded area) by grinding, or inserting a carbon core material 5 into the inner circumferential surface and carbonizing the outer circumferential surface as shown in Fig. 6. A circular carbon base material 7 covered with a cylinder 6 is filled with B ₄ C powder 2 whose surface is coated with ethyl silicate, and the B ₄ C powder is sintered by hot pressing and at the same time bonded to the base material. In the latter case, it is necessary to apply a mold release agent 8 such as BN and perform hot pressing in order to prevent the reaction between B ₄ C and the inner surface of the cylinder that covers the outer peripheral surface of the circular carbon base base material. . The mechanical seal ring of this invention compensates for the weak impact resistance of B ₄ C with a carbon base, and uses B ₄ C as a mechanical seal ring with strong impact resistance.
Can be used under harsher conditions than simple mechanical seal rings. In addition, we manufacture large seal rings that have superior wear resistance and are significantly lighter at approximately 1/7 of the weight of the normally used single mechanical seal rings made of cemented carbide (WC-CO), which could not be used in the past. This is also possible, and since the carbon base material is easy to mechanically process, it has the effect of being easy to form into the required shape. According to the method of the present invention, sintering of B ₄ C and adhesion to the carbon base material can be simultaneously performed using the hot pressing method, and in addition, in a product that has completed the sintering of B ₄ C.
B ₄ C reacts with the carbon base material and can be strongly bonded to the base material, and the carbon in this B ₄ C-carbon structure can be mechanically treated and used as a mechanical seal, making it possible to process conventional ceramics or Compared to the brazing method, it not only makes the manufacturing process much easier, but since it does not require brazing adhesives, _B4C material retains its excellent properties such as high density, wear resistance, and corrosion resistance. Yes, also B ₄ C
The thickness can be adjusted as desired, and even in the case of a thin film, it has the effect of ensuring reliable adhesion without causing cracks.
Furthermore, B ₄ C that constitutes the seal ring of the present invention has greater hardness and bending strength than conventional B ₄ C.
It also has the effect of being able to obtain a product with almost no porosity and high wear resistance and corrosion resistance at a relatively low temperature of 1950°C, making it possible to obtain an excellent ceramic seal ring for mechanical use.

[Brief explanation of the drawing]

Figures 1 to 3 are X-ray diffraction patterns of the B ₄ C sintered body, B ₄ C adhesive layer, and C layer of sample No. 5, and Figures 4 to 3 respectively.
FIG. 6 is an enlarged cross-sectional view showing how the B ₄ C coating method is applied to the seal ring base material of the mechanical seal of the present invention.

Claims (1)

[Claims] 1. A circular ring B ₄ C— on one end surface of the circular carbon body.
A mechanical seal ring characterized by a strongly bonded SiC sintered body. 2. A method for producing a mechanical seal ring, which comprises sintering B ₄ C powder whose surface is coated with ethyl silicate on a carbon seal ring base material using a hot press method, and at the same time bonding the base material to the base material. 3 A carbon seal ring base base material is shaped with a concave groove around one end surface, and hot press sintering of B ₄ C powder whose surface is coated with ethyl silicate is carried out within the concave groove. A method for manufacturing a mechanical seal ring according to claim 2, characterized in that: 4. Hot press sintering of B ₄ C powder whose surface is coated with ethyl silicate is performed on a circular carbon base material with a carbon core material inserted on the inner peripheral surface and a carbon cylinder on the outer peripheral surface. A method for manufacturing a mechanical seal ring according to claim 2.