In the field of modern machining, Carbide Inserts have become key tool materials with their excellent properties and wide applications. A comprehensive and in-depth analysis of its application from the basis of material science to the processing technology is helpful to fully understand and play the important role of cemented carbide blades in the manufacturing industry, and promote the continuous progress and innovation of processing technology.

First, the material science basis of cemented carbide blades

Composition and phase structure

Carbide inserts are mainly composed of a hard phase and a bonded phase. The hard phase is usually tungsten carbide (WC), titanium carbide (TiC), tantalum carbide (TaC) and other carbides, which have the characteristics of high hardness, high melting point and high wear resistance, and are the key factors to give the cutting performance of the blade. Among them, WC is the most commonly used hard phase, and its crystal structure is hexagonal close-packed, with good strength and toughness. TiC has higher hardness and wear resistance, which can improve the cutting ability of the blade on high-hardness materials. TaC can improve the high temperature performance and oxidation resistance of the blade.

The bonding phase generally uses cobalt (Co), nickel (Ni) and other metals, and its main role is to bond the hard phase particles together to form a whole with a certain strength and toughness. As a bonding phase, Co has good wettability and high strength, which can form a firm bond between the hard phase particles, and also play a certain cushioning role in the cutting process to improve the impact resistance of the blade. By adjusting the type and proportion of the hard phase and the bonding phase and adding trace amounts of other alloying elements, the performance of the cemented carbide blade can be accurately controlled to meet the needs of different processing conditions.

Relationship between microstructure and properties

The microstructure of carbide inserts has a decisive influence on their performance. At the microscopic level, the hard phase particles are evenly distributed in the binder phase matrix, forming a structure similar to that of composite materials. Factors such as the size, shape, distribution uniformity of the hard phase particles and the interface bonding state between the adhesive phase will affect the hardness, strength, toughness and wear resistance of the blade.

For example, a smaller hard phase particle size can increase the number of hard phases per unit volume, thereby improving the hardness and wear resistance of the blade. However, too small particle size may cause the interface area to increase, weaken the interface bonding strength, and reduce the toughness of the blade. Therefore, it is necessary to seek an optimal balance between hardness and toughness. In addition, the shape of the hard phase particles will also affect the performance of the blade, such as spherical particles are conducive to improving toughness, and angular particles are more conducive to cutting and chip formation. Through advanced powder metallurgy process, the microstructure of carbide blades can be precisely controlled, and the blade materials with excellent comprehensive properties can be prepared.

Second, the preparation process of cemented carbide blade

Powder metallurgy process

Powder metallurgy is the main process for preparing carbide inserts. The process includes powder preparation, mixing, pressing, sintering and so on. Firstly, the high purity and fine particle size hard phase and binder phase powder are prepared by various methods. For example, WC powder can be obtained through the reduction and carbonization process of tungsten ore, and then these powders are fully mixed in the ball mill and other equipment according to a certain formula ratio, so that the hard phase and the binder phase powder are evenly distributed.

The mixed powder is pressed into a body with a certain shape and size, and cold isostatic pressing or molding is usually used in the pressing process to ensure the density uniformity and dimensional accuracy of the body. Finally, the billet is sintered at a high temperature, the sintering temperature is generally between 1300℃ -1500 ℃, in the sintering process, the bonding phase metal melts and infiltrates the hard phase particles, through atomic diffusion and solid reaction, so that the hard phase particles form a firm bond, the billet gradually densification, and finally form a carbide blade with the required performance. In the sintering process, the performance of the blade can be further optimized by controlling the atmosphere and adding sintering additives, such as sintering in a vacuum or hydrogen atmosphere can reduce the content of impurities in the blade and improve its quality.

Coating technology

In order to further improve the cutting performance and service life of cemented carbide blades, coating technology is widely used. The coating is the deposition of one or more layers of thin film materials with special properties on the surface of the cemented carbide blade, such as titanium nitride (TiN), titanium aluminum nitride (TiAlN), titanium carbonitride (TiCN) and so on. The functions of the coating mainly include improving the hardness and wear resistance of the blade, reducing the friction coefficient, and enhancing the oxidation resistance and thermal shock resistance of the blade.

There are two main coating processes: chemical vapor deposition (CVD) and physical vapor deposition (PVD). The CVD process is to deposit the gaseous coating material on the surface of the blade through a chemical reaction at high temperature, which has the advantage of uniform coating thickness and strong binding force, but due to the high deposition temperature (usually between 800℃ and 1000℃), it may lead to a decline in the performance of the blade matrix. The PVD process uses physical methods (such as sputtering, evaporation, etc.) to deposit the coating material on the surface of the blade at a lower temperature (generally below 600 ° C). The process has little thermal impact on the blade matrix and can maintain the original performance of the blade, but the coating thickness is relatively thin and the binding force between the coating and the matrix is relatively weak. In practical applications, the appropriate coating process and coating material can be selected according to the specific use and performance requirements of the blade.