Comparison of erosion resistance of hard and brittle materials processed by low-temperature micro-abrasive gas jet

Abstract

Objectives: During low-temperature micro-abrasive air jet machining, the mechanical properties of materials undergo changes, making the material more prone to brittleness and erosion removal. Comparative experiments were conducted on the low-temperature micro-abrasive air jet machining of hard and brittle materials to investigate their machining performance at low temperatures and to indentify materials with better erosion resistance under such conditions. Methods: Low-temperature micro-abrasive air jet machining comparative experiments were conducted on five materials: silicon carbide (SiC), silicon nitride (Si3N4), yttrium-stabilized zirconia (YSZ), 99% alumina (Al2O3), and quartz glass. First, the materials were pretreated using the same surface treatment method, and a material removal model was established to identify the factors affecting the changes in low-temperature properties. Next, micro-abrasive air jet machining experiments were performed at 77 K to investigate the effects of different process parameters—including machining pressure, impact machining angle, and machining time—on erosion removal rates, low-temperature erosion groove three-dimensional morphology, and surface profiles of the five materials. Finally, the three-dimensional morphology of the low-temperature erosion grooves and the surface profiles of the materials were compared and analyzed to evaluate the erosion resistance of each material during low-temperature machining. Results: The processing performance of the five materials at low-temperatures showed the following trends: (1) As the processing pressure increased, the surface groove volumes of all five materials gradually increased. However, the surface groove volumes of Si3N4 and SiC did not increase significantly. (2) As the impact angle increased, the surface groove volumes of all five materials also gradually increased. The groove volume reached its maximum value when the impact angle approached a vertical processing angle. Si3N4 exhibited the smallest low-temperature erosion groove volume under these conditions. (3) All five materials exhibited increased brittleness at low temperatures, with minimal plastic deformation due to their high hardness. At smaller impact angles, surface material removal was limited, resulting in smaller low-temperature erosion grooves. As the impact angle increased, material removal transitioned from plastic deformation to surface fracture. At the maximum impact angle (90°), the material removal became most evident, and the erosion groove reached their largest volume, exhibiting a typical brittle removal mode. (4) Under the same processing parameters, the erosion removal rates of the five materials increased sequentially. The erosion removal rate of silicon nitride was the smallest, with a maximum low-temperature erosion groove depth of only 20 μm. Silicon carbide's erosion removal rate was similar to that of silicon nitride material, but the erosion removal rate of quartz glass material was the highest, considerably exceeding that of the other four materials. (5) As the number of machining cycles increased, the surface groove volumes for all five materials also gradually increased. (6) The groove shape formed on the surface of silicon nitride was not obvious, consisting mainly of small pits that could not form complete microchannels. Additionally, the surface of silicon nitride remained relatively flat, with minimal material removal, resulting in the smallest depth of the low-temperature erosion grooves. (7) After the erosion processing, quartz glass formed an obvious "U"-shaped groove, which could be clearly observed under a microscope. In contrast, the grooves of the other four materials had no fixed shape and appeared relatively flat. Upon magnification, small "U"-shaped grooves and similar "V"-shaped grooves were observed locally on the surfaces of the four materials, indicating that the morphological changes during erosion processing were relatively complex. Conclusions: The low-temperature micro-abrasive air jet machining comparative experiment was used to analyze the material erosion removal rates, three-dimensional morphology, and surface profiles of low-temperature erosion grooves. Among the five hard and brittle materials tested, silicon nitride material exhibited the smallest erosion groove volume, the lowest erosion removal rate, and the highest erosion resistance. These findings provide a foundation for future research into low-temperature micro-abrasive air jet technology for masks.

Keywords

• hard-brittle materials
• low-temperature
• abrasive air jet
• erosion resistance
• erosion removal rate