Polycrystalline diamond compacts (PDCs) for cutting tools are currently being developed toward size upsizing, quality optimization, uniform performance, and diversified shape structures. The large-diameter PDC not only reduces the cost per unit area, improves the utilization rate, but also better meets the requirements for users to manufacture various types of blades.
Due to the strong product specificity and stable and reliable quality, domestic PDCs for cutting tools have a certain gap in terms of quality, specifications and varieties compared with foreign advanced levels in terms of synthesis and application due to the limitations of formulation and technology. In 2010, China independently developed and developed a PDC for 45mm cutting tools. Its performance in some varieties has reached the level of similar foreign products, which has greatly promoted PDC tool materials.
High-end applications. After continuous exploration in recent years, the product quality, market competitiveness, and market share of domestic PDCs have been greatly improved, but the gap between PDC diameters and foreign products remains large.
Recently, we used the nano-binding agent technology  to break through the technical bottleneck in the field and synthesized a PDC with a diameter of mm55 mm for tooling on a hexahedral press. After performance testing, it is equivalent to the performance of similar foreign products.
I conditions and processes
1.1 Experimental Equipment and Methods
In this experiment, six face presses were used to synthesize. In order to solve the problem of axial pressure loss in the sintering process, a hydraulic control system for heating and maintaining the pressure in six directions was used . In order to synthesize PDC with higher quality, nano-binder technology was used, high-grade diamond powder with double peak distribution was selected, and high-temperature and high-pressure sintering was used to finally obtain PDC products with excellent properties.
1.2 Diamond size selection
The grain size of diamond has a great influence on the wear resistance and breakage resistance of PDC. The finer particle size has higher wear resistance and compressive strength, but fine-grained diamond is not easy to sinter; the coarser the diamond particle size, the better the PDC sintering performance and the stronger the ability to resist mechanical abrasion; using double peaks and multiple peaks The distributed diamond powder can effectively increase the wear resistance, heat resistance and impact resistance of the PDC and prolong the service life of the tool. Experiments show that the use of diamonds with different peak sizes in a certain proportion will increase the quality of PDC. Adding a small amount of fine-grained diamond particles to the raw material will improve the overall performance of the tool.
1.3 Carbide Material Selection
The properties of cemented carbides depend primarily on the alloy’s cobalt content, WC grain size and sintering pressure, temperature and time. In general, the finer the WC particle size, the higher the hardness and the higher the compressive strength. After the hard alloy is refined, the hardness of the hard alloy is improved. The higher the hardness of the hard alloy layer, the closer to the elastic modulus and thermal expansion coefficient of the polycrystalline diamond layer, so that the polycrystalline diamond-carbide interface can be reduced. Stress: 1, reduce the probability of deformation and delamination of the composite sheet.
1.4 Assembly Block Assembly Structure
The experimental assembly block assembly structure shown in Figure I.
The pyrophyllite ring and dolomite liner are used as the heat transfer medium for the synthesis block, and the carbon tube, salt pipe, and salt film are used as the internal pressure media to ensure that the high pressure and high temperature fields of the composite composite sheet are more stable. In order to make the temperature and pressure distribution of the synthesis chamber uniform and meet the requirements of large-diameter synthetic PDC, the conductive steel ring adopts a large-diameter thin-wall structure, the core is filled with a dolomite core and a wax ring is set around the core to achieve insulation at both ends and avoid burning. Hammer; Shaped electrical conductors are made of materials with higher resistivity. By changing their shape and size, the temperature gradient of the synthesis chamber is reduced; tubes and pieces in the carbon tube are suppressed by white salt materials, and the salt is used for high temperature expansion and flow characteristics. Reduce the pressure gradient in the synthesis chamber.
1.5 Selection of Synthetic Sintering Process
The sintering process curve adopts one step-up, one-time heating and final slow cooling process scheme. The sintering process P-curve is shown in Figure 2. According to the PDC polycrystalline compact size and T. arts requirements, the sintering process parameters