What are the causes of surface burning and cracking on cemented carbide rings?
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If the ring-shaped grooves on the sealing surface are caused by vaporization on that surface (with the liquid still present in the sealing chamber), then the burning or even cracking of the surface of the cemented carbide ring occurs when the medium outside the sealing surface – that is, within the sealing chamber – has vaporized or been evacuated. In such cases, the friction pair operates under dry or semi-dry friction conditions, resulting in a sharp increase in the temperature of the sealing surfaces and overheating of the friction pair. Once liquid reappears, the friction pair is rapidly cooled, generating significant thermal stress. In materials with good thermal conductivity and high strength (such as tungsten carbide), signs of polishing and discoloration may appear, and cracks sometimes form on the sealed surfaces ； Radial cracks appear on the surfaces of materials with poor thermal conductivity and low strength (such as various surfacing hard alloys). Ring-shaped grooves appear on the surface of the ring regardless of the material.
The burning and cracking on the surface of the cemented carbide ring are mainly caused by the vaporization or evacuation of the sealing medium, which leads to the friction pair entering a dry or semi-dry friction state; as a result, the temperature of the friction surfaces rises sharply, resulting in overheating. When the heat generated by friction accumulates to a certain level, the re-introduction of a liquid medium causes the surfaces of the frictional pair to cool down rapidly, generating significant thermal stresses. This, in turn, leads to damage such as polishing, discoloration, and cracking on the material surface. Materials with high thermal conductivity and strength (such as tungsten carbide) may show polishing and discoloration, while materials with low thermal conductivity and strength are more prone to radial cracks. At the same time, ring-shaped grooves may form on the surface of the ring, regardless of the material type. .
Thermal cracking is primarily related to temperature: 1. Rapid temperature increases; 2. Temperature rises due to overload or vaporization, which leads to a loss of lubrication; 3. Temperature increases as a result of dry operation under conditions other than those designed for the system
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