The complete production process of cemented carbide powder metallurgy encompasses core steps such as ball milling of tungsten carbide-cobalt powders, pressing and forming, and debinding/sintering. The process parameters and compatibility of auxiliary materials at each stage directly determine the hardness, toughness, and service life of end products like cutting tools, drill bits, and wear-resistant components. While most manufacturers focus heavily on the quality of key raw materials like tungsten carbide and cobalt powders, they often overlook stearic acid—a critical process aid. Stearic acid plays an indispensable role throughout the entire production chain, from feedstock preparation to pressing, demolding, and debinding. It is essential for ensuring stable mass production and high-quality finished goods in cemented carbide manufacturing.
In the wet ball milling process, ultrafine tungsten carbide powder exhibits extremely high surface energy, leading to severe agglomeration. This causes uneven distribution of mixture components and excessive particle size variation, resulting in significant performance fluctuations and unstable quality of the final sintered cemented carbide products. Adding an appropriate amount of high-purity stearic acid effectively adsorbs onto the surfaces of WC and cobalt powder particles, significantly reducing surface free energy. This completely resolves powder agglomeration and sedimentation, ensuring uniform dispersion of all raw materials, substantially improving milling efficiency, and guaranteeing consistent particle size distribution across batches. Particularly in production systems using n-hexane as the wet milling medium, stearic acid enhances powder wettability and slurry suspension stability, precisely optimizing core performance metrics such as cobalt magnetization and coercivity, laying a solid foundation for high-quality finished products.
In the compaction process, stearic acid primarily serves as a high-efficiency lubricant. It forms a uniform, dense lubricating film on the surface of powder particles, effectively reducing friction between particles and between the powder and the mold wall. This improves overall powder flowability, ensuring uniform filling throughout the mold cavity for consistent green compact density and precise dimensions. Additionally, it reduces the required compaction pressure and minimizes equipment wear. By addressing root causes, it prevents common defects such as delamination, cracking, chipping, and deformation. The process also significantly enhances ejection performance, eliminating issues like part sticking or surface damage, while improving green compact structural integrity. This facilitates downstream handling and precision machining, substantially lowering defect rates and boosting production yield.
As a key activating component of wax-based binders, stearic acid significantly enhances flowability and powder wettability, making it ideal for diverse forming processes such as extrusion and injection molding to meet the production needs of various cemented carbide grades. During subsequent debinding, its moderate volatilization temperature and complete thermal decomposition enable rapid breakdown and release. This creates uniform gas channels within the green body, ensuring efficient and thorough binder removal while minimizing defects like residual carbon, black spots, and voids. Consequently, it prevents post-sintering issues such as internal porosity, uneven hardness, and performance imbalance, guaranteeing dense microstructure and stable properties in final cemented carbide products.
The cemented carbide industry demands strict specifications for stearic acid, including high purity, iodine value, and ash content. Ordinary low-purity stearic acid contains high impurities and poor batch stability, leading to issues such as poor powder dispersion, excessive residual carbon after de-binding, and unstable production conditions. These problems cause significant variations in product toughness, chipping, fracture susceptibility, and reduced service life across batches. By selecting metallurgical-grade stearic acid with high purity, low ash, and stable performance—and strictly controlling precise dosing—manufacturers can ensure consistent feedstock dispersion, optimize green body quality, eliminate process risks at the source, and guarantee batch-to-batch product consistency.
In summary, although stearic acid is a trace additive in cemented carbide production, it profoundly impacts the stability and final quality of the entire powder metallurgy process. For manufacturers, selecting high-quality metallurgical-grade stearic acid is critical to ensuring consistent output, minimizing defect rates, enhancing core performance (wear and impact resistance), and strengthening market competitiveness.
guiz liutong 25-8-24