Generally heat sets, inserts, bonding, welding carbide seal ring at work are inadequate, and the overall Carbide seal ring can avoid leakage, heat distortion, electrochemical corrosion these deficiencies. It mainly has the following use characteristics:
1. Application dry at high temperatures
Solid carbide end face of the sealing ring does not change the appearance of flatness due to the difference in thermal expansion coefficients of different materials during temperature changes. XYTR solid carbide alloy material manufactured by the seal ring face flatness after polishing measured on standing for a long time, almost no change in flatness. Use whole in 380 ℃ high temperature carbide ring pump in operation after 8000 hours, the amount of deformation test, still within the tolerance range.
Solid carbide seal ring when used in high temperature, high temperature resistant materials should be selected for the secondary seal. PTFE general, in order to prevent PTFE V-ring softening at high temperatures, should be added to a V-shaped metal ring in the middle of them, play a role in skeleton, in order to ensure the reliability of sealing. In addition, the PTFE resin impregnation abroad asbestos, flexible graphite and carbon fiber materials such as seals.
2. adapted to operate at a high speed, high pressure
High-speed mechanical seal is the main risk of thermal stress cracking, thermal deformation and friction material to heat up more than the limit. Solid carbide seal ring material uniform, will not occur due to the centrifugal force during operation at a high speed greater unbalance caused by vibration and sealing ring through the big phenomenon. At the same time, its good thermal conductivity, thermal deformation and small, and therefore suitable for use as high-speed ring pump. Japan Nikkiso Co., high-speed pumps on the use of such structures.
Mechanical seal at medium pressure and high-pressure work, mechanical and thermal deformation of the friction pair of mechanical seals affect the function and use of the main factors of reliability. Solid carbide seal ring allows such deformation decreases. In some foreign high or ultra-high pressure seal ring used, often using solid carbide, and a variety of open trenches hydrodynamic structure at its end face. Such a structure for atomic power stations on the main circulating pump has been quite mature experience, this is generally not a cobalt alloy for bonding metal, instead of using short half-life nickel as a binder metal.
3. suitable for use in medium containing particles
Medium solids containing particles or dissolved impurities are likely to enter or deposited after the evaporation of the solvent in a sealed surface, not only cause severe abrasive wear, also enables the sealing surface to produce localized heating, resulting in thermal cracking. If the medium is corrosive electrolyte, then, will also chemical corrosion and electrochemical corrosion occurs in the sealing ring surface. In addition, if the temperature of the medium and relatively high, the sealing problem is more complex. Mechanical seal friction medium containing solid particles generally used carbide materials, is currently the most used carbide.
Heat sets, inserts, bonding, welding assembly of the seal ring due to temperature and pressure changes, particulate impurities will enter the assembly of the gap, resulting in seal failure. The Solid Carbide will not appear on this phenomenon, while its thermal deformation is small, good thermal conductivity, thermal cracking possibility of decreased production, it will not produce galvanic corrosion on a sealing ring. The cobalt-containing alloy and corrosion resistance is poor, the available Ni - Cr alloy as an alternative bonding metal drill, in order to improve the tungsten carbide based cemented carbide corrosion resistance. Furthermore, to enhance its thermal malleability and corrosion resistance may be added titanium carbide and tantalum carbide, such alloy products, are accessible production.
Assembled sets and other heat carbide seal ring despite some shortcomings, but as long as the design is reasonable, correct selection, quality assurance, but still widely used in the current structure, and can get better results. But for solid carbide seal ring and heat set, inserts, bonding, welding carbide seal ring, compared with small deformation, good thermal conductivity, easy to crack, reducing leaks and a series of features, accessible alloy XYTR materials such seal ring on pump equipment, have achieved good results.