Tungsten crucible is one of the typical applications of tungsten material, in addition to the performance of the material itself, the influence of machining accuracy on the final performance of the crucible can not be ignored, especially in the context of increasingly strict requirements for high-precision manufacturing and thermal field control, processing quality has become one of the key factors to evaluate the reliability and practicability of the crucible.
First of all, machining accuracy is directly related to the accuracy of geometric dimensions and structural integrity. In the use of crucibles, the size of the inner cavity needs to be highly consistent to ensure that the melt or crystals are evenly heated and stressed in the crucible. If there is uneven wall thickness, concentricity deviation or elliptical deformation during machining, it can lead to uneven local temperature distribution, which can lead to problems such as melt flow disorders, crystal defects or thermal stress concentrations. For example, in the sapphire crystal growth process, the temperature gradient control accuracy is often measured in millimeters, and once the inner wall finish or dimensional tolerance of the W crucible exceeds the specified range, it will seriously interfere with the stability of the crystal growth interface.
Secondly, the surface roughness of tungsten crucible has a significant effect on its thermal conduction efficiency and chemical stability. The overly rough inner wall not only increases the microscopic irregularity of the contact interface with the melt, but also increases the thermal resistance of the interface, reduces the heat conduction efficiency, leads to the lag of temperature distribution, and affects the stability of the process. In addition, rough surfaces are more susceptible to adsorbing impurities and oxides, reacting with the melt at high temperatures, and contaminating the material being treated, especially in the preparation of high-purity metals or semiconductor materials. Therefore, in high-end applications, W crucibles often require precision turning, inner wall polishing and even electrolytic polishing to ensure that their surface is mirror-level flatness and cleanliness.
In addition, machining accuracy also has an indirect effect on the mechanical strength and thermal stress relief ability of tungsten crucibles. Tungsten material exhibits a certain degree of brittleness at room temperature, and once stress concentration points or microcracks (such as cutting lines, residual indentations, etc.) appear during processing, it is easy to become the starting point of crack propagation in subsequent high-temperature cycles, resulting in premature failure of the crucible. High-precision machining can effectively reduce the existence of internal residual stress and surface defects, thereby improving the thermal shock resistance and overall structural stability of the product.
In order to achieve high machining accuracy of tungsten crucibles, advanced CNC turning, isostatic pressing and precision sintering technologies are usually required, supplemented by multiple inspection procedures, such as three-coordinate inspection, laser scanning measurement and ultrasonic flaw detection, to ensure that each product meets the design standards. In special application scenarios, mirror grinding or chemical passivation technology may also be used to optimize the crucible surface to improve its resistance to contamination and corrosion.
