This article presents a review of the current research into the diamond retention capacity of metal matrices, which largely determines the service life and working performance of diamond tools. The constitution of diamond retention capacity, including physical adsorption force, mechanical inlaying force, and chemical bonding force, are described. Improved techniques are summarized as three major types: (1) surface treatment of the diamond: metallization and roughening of the diamond surface; (2) modification of metal matrix: the addition of strong carbide forming elements, rare earth elements and some non-metallic elements, and pre-alloying or refining of matrix powders; (3) change in preparation technology: the adjustment of the sintering process and the application of new technologies. Additionally, the methods used in the evaluation of diamond retention strength are introduced, including three categories: (1) instrument detection methods: scanning electron microscopy, X-ray diffractometry, energy dispersive spectrometry and Raman spectroscopy; (2) mechanical test methods: bending strength analytical method, tension ring test method, and other test methods for chemical bonding strength; (3) mechanical calculation methods: theoretical calculation and numerical computation. Finally, future research directions are discussed.

Based on the discrete element method, this study has simulated the movement of materials in the plated barrel using EDEM software to investigate the effect of the impact medium with different particle sizes on the mechanical deposition plating. The simulation analyzed the interaction between five impact mediums with different particle sizes (2, 3, 4, 5, and 6 mm) and the base body while determining the particle size ratio of the impact medium. The rationality of the particle size ratio was verified by the simulation analysis of the interreaction of two groups of mixed particle size impact medium and the base body. The samples of mechanically deposited zinc coating were prepared. The average thickness, relative density, and average deviation of the coating were measured. The results show that When the particle size is 2 and 3 mm, the effective collision frequency of the materials is higher. When it is 3, 4, and 5 mm, the kinetic energy of collision between materials fluctuates evenly. When it is 4 and 5 mm, the collision contact force of the materials changes regularly. Consequently, the obtained particle size ratio (second group) is 2 mm 23%; 3 mm 23%; 4 mm 23%; 5 mm 27%; and 6 mm 4%. Compared with mixed impact media with 20% of each of the five particle sizes (first group), in the second group of assorted particle size simulation test, the collision frequency between materials is high. The contact force changes more regularly between materials. The average thickness, relative density, and average deviation of the mechanically deposited galvanized layer are consistent with the simulation results of the two groups of mixed particle sizes. The average thickness and relative density of the galvanized layer in the second group are higher, the average deviation is smaller, and the compactness and uniformity are the best.