A niobium strip is formed into crucibles for the manufacture of synthetic diamonds in a wide range of applications. In some cases, block synthetic diamonds are required, which are obtained by placing the carbon material in a niobium crucible and exposing it to high pressure and high temperature .
Niobium crucibles are made of sheet material by deep drawing. The quality and surface quality of these crucibles are critical to the final quality of synthetic diamonds. To meet the demands of deep drawing and quality requirements for synthetic diamonds, Raytec metal engineers have made significant improvements to our niobium sheet, which solves the problems and problems associated with making crucibles.
Niobium Crucible Defect Prevention
There are many variables to consider when designing a deep drawing process. Incorrect configuration at any stage can lead to defects in the final deeply drawn component.
• Crumple in the flange due to low holding force.
• Wall wrinkles occur when the wrinkled flange is pulled into the cup or the gaps are very large.
• Tearing occurs due to high tensile stresses that cause thinning of the sheet. The gap also occurs due to sharp angular radii, high length to diameter ratios (L / D), high pressure gasket loads and high stamp loads.
• An earring occurs when a material is anisotropic (ie, directivity in properties)
• Surface scratches occur if the punch and die are not smooth or if process grease is insufficient.
• Radial cracks on the flanges and the edge of the bowl due to insufficient ductility of the metal.
• Orange peel (surface roughness) is found in coarse-grained metals.
The most common material defect problem is the orange peel due to the coarse grain size. A related microstructure of niobium may show poor flatness and smoothness of a deeply elongated cup, since each grain tends to deform independently and unevenly. Poor flatness and / or smoothness can lead to the formation of synthetic diamond, which requires excessive grinding. The coarse-grained structure can also cause sheet tearing during deep drawing operations.