欧美人妻精品一区二区三区99,中文字幕日韩精品内射,精品国产综合成人亚洲区,久久香蕉国产线熟妇人妻

carbide valves are widely needed?in demanding conditions such as powder transport, wear resistance becomes a crucial performance assessment element?for valves.

What is Tungsten Carbide Demanded in Valves? 2

The wear forms on valves

Based on the conditions and mechanisms of friction, wear can take various forms, with common types including abrasive wear, adhesive wear, fatigue wear, corrosive wear, and erosive wear.

Common parameters used to characterize material wear performance include wear volume, wear rate, wear depth, wear resistance, and relative wear resistance. The fundamental requirement for abrasion resistance is that the surface of the object must have high hardness (surface hardness should exceed the hardness of the abrasive). Additionally, it should exhibit good oxidation resistance at the operating temperature. The most effective way to control or minimize wear is to enhance material hardness and wear resistance.

Sintered tungsten carbide has high strength, a smooth surface finish, and a lower coefficient of friction compared to steel when used in conjunction with other materials. This significantly reduces contact surface frictional forces, effectively lowering operating torque.

Material features of carbide

Whole sintered carbide?is produced by high-temperature heating of a mixture of tungsten and carbon. The hardness of most tungsten carbides is very high, with microhardness second only to diamond. It has a melting point of 2870°C and a boiling point of 6000°C, with a relative density of 15.63 (at 18°C). It is resistant to decomposition at high temperatures and exhibits excellent oxidation resistance.

Field investigations indicate that tungsten carbide demonstrates wear resistance in situations such as abrasive wear, erosive wear, and abrasion, which is about 100 times higher than that of tool steel, stainless steel, iron, and brass. It has 2-3 times the rigidity of steel and 4-6 times the rigidity of cast iron and brass, with impact resistance similar to that of quenched tool steel.

What is Tungsten Carbide Demanded in Valves? 3

The reason carbide is needed in valves

In conditions involving high temperature, high pressure, strong corrosion, and slurries or powders with solid particles such as in gasification and polycrystalline silicon, the sealing surfaces of conventional hard-sealed ball valves, V-port control valves, coal powder control valves, butterfly valves, and slide valves use carbides as the sealing materials for the valve disc and seat. However, due to the limitations of the sprayed tungsten carbide coating—thickness <2mm, hardness <60HRC, and coating adhesion to the substrate <1000psi—the spraying process is typically conducted under harsh conditions at temperatures as high as 10000°C. Valve lifespans are challenging to guarantee for 10,000 cycles, making it difficult to meet the long-term stable production requirements of systems handling coal chemical slurries and polycrystalline silicon powders.

On the other hand, the strength of sprayed tungsten carbide mainly relies on the base material, and when the coefficients of thermal expansion of the two materials are significantly different, the usage is limited by temperature and cannot exceed 450°C. The valve performance has seen significant improvements with the adoption of integral sintered carbides for the valve disc and seat in new types of hard-sealed ball valves (Figure 1), V-port control valves (Figure 2), coal powder control valves (Figure 3), butterfly valves (Figure 4), and slide valves, addressing these challenges.

What is Tungsten Carbide Demanded in Valves? 4

Fig1 Sealing ball valve

What is Tungsten Carbide Demanded in Valves? 5

Fig2 control valve

(1) High Hardness: With a hardness greater than 80HRC, it can withstand the high-speed scouring of multiphase particle media such as water-coal slurry, coal powder, and silicon powder.

(2) High-Temperature Resistance: Capable of prolonged operation at temperatures up to 750°C, it is not limited by temperature in terms of strength, adhesion, and thermal expansion. This completely meets the requirements of high-temperature conditions, such as those encountered in coal chemical processes.

(3) High Pressure Resistance: The transverse fracture strength of integral sintered tungsten carbide reaches 4000MPa, more than 10 times the strength of conventional steel. It can operate long-term under working pressures up to 25MPa.

(4) Corrosion Resistance: Integral sintered tungsten carbide exhibits stable chemical properties. It is insoluble in water, does not react with hydrochloric acid and sulfuric acid, and is not dissolved even in aqua regia. This corrosion resistance satisfies the special requirements of industries such as coal chemical processing.

What is Tungsten Carbide Demanded in Valves? 6

Fig3 Coal powder control valve

carbide valve

Fig4.?Butterfly valve

(5) Wear Resistance: The high hardness and stability of integral sintered tungsten carbide ensure excellent anti-wear properties for sealing components. This meets the special wear requirements of media such as coal powder and organosilicon (silicon powder particle hardness is 62HRC).

(6) Erosion Resistance: Conventional valves with sprayed tungsten carbide coatings on sealing surfaces often suffer severe erosion, exhibiting honeycomb patterns within a month under conditions of 250°C and losing functionality completely. In contrast, V-port control valves and coal powder control valves, which use integral sintered tungsten carbide as control components, have a lifespan of 12 months under 450°C (other conditions remaining the same). Disc valves and slide valves, subjected to more than 300,000 switching cycles, fully meet the long-term operational requirements of industries such as coal chemical processing for 8000 hours.

(7) High-Temperature Flexibility: Both the ball and seat are made of integral sintered carbides, with coefficients of thermal expansion ranging from 1/3 to 1/2 of conventional steel. This effectively prevents the common issue of valve sticking at high temperatures, ensuring excellent operational performance under high-temperature differential conditions.

(8) Low Friction: The use of sintered carbide?anti-wear pads not only extends the high-temperature lifespan of the pads but, due to their lower friction coefficient, typically only 1/3 to 1/2 of conventional paired materials. This significantly reduces frictional forces between components, lowering valve operating torque.

 

???????

Integral sintered carbide?possesses high strength, high hardness, a high melting point, stability, a low friction coefficient, wear resistance, erosion and cavitation resistance, and corrosion resistance. Manufacturing wear-resistant valve sealing components for demanding operating conditions has enhanced the applicability of valves, expanded their range of use, prolonged their operational lifespan, ensured various performance indicators, and met the development needs of the chemical industry.

???? ???????

?? ??? ??? ????? ????? ??????????. ?????? ????????? ???? ????? ?? *

胸大裸体美女视频| 精品国产Av无码久久久一区二区| 三级片成人京东热五月天| 青春草在线视频观看| 澳门一区二区免费下线观看| 男女真人牲交高潮全过程| 白虎鲍鱼抠逼免费看| 亚洲 欧美 日韩 主播| 日本一区二区在线高清| 亚洲高清中文字幕一区二区三区| 欲色福利网免费在线播放| 日本a国产精品久久久久| 五月天亚洲激情综合av| 欧美人与兽大屌肛交爆菊| 日本高清一区二区三区在线观看| 日韩午夜免费av在线| 一区二区三区中文欧美| 欧美黄色三级成人小视频| 九热中文字幕在线| 中文字幕av一区二区三区哈| 啦啦啦视频在线手机播放| 少妇无套带白浆嗯呢啊污| 成人男女做爰免费视频网| 久操视频中文字幕在线观看| 制服丝袜国产在线第一页| 91性潮久久久久久久久| 欧美在线A片一区二区三区| 欧美一区亚洲一区视频在线观看| 亚洲综合网伊人中文| 鸡巴插骚逼视频欧美风格| 大鸡巴猛插小穴视频| 亚洲欧美中文字幕第二十| 久久无码免费视频| 久久99热人妻偷产精品| 日本熟妇 bbw| 男人添女人下面免費视頻| 国产一区二区三区 韩国女主播| 插女人下面高潮视频| 国产色哟哟精选在线播放| 日韩美女在线视频一区不卡| 午夜国产精品午夜福利网|