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Vacuum Brazing Furnace

What is Vacuum Brazed Diamond

Vacuum brazed diamond tools have attracted great interest in research and product development from industry experts and manufacturers because of their high connection strength and high cutting edge. At present, Ni-Cr-B-Si solder is mostly used to braze diamond to make single-layer diamond tools. However, Ni-Cr solder can cause great thermal damage to diamond. Cu-Sn-Ti can wet diamond. However, copper-based solder has poor wear resistance and high-temperature performance. The active element Ti is necessary for diamond brazing. An appropriate amount of tin can control the melting point of the solder. Ni, which has better high-temperature performance, is added to the Cu-Sn-Ti alloy. The element can not only improve the high-temperature performance of the solder, but also solid-solution strengthen the copper-based solder, which is beneficial to the heat resistance and wear resistance of the tool. Secondly, the C element of diamond can dissolve into the nickel-based alloy in a small amount but can hardly dissolve into it. Copper-based alloys may increase interface reactions and wettability. Cu and Ni elements are infinitely soluble in each other and will not produce an unfavorable brittle phase, but the addition of Ni element will reduce the activity of titanium. However, as the titanium content increases, on the one hand, the wettability of the solder to diamond is improved, on the other hand, the strength and brittleness of the solder itself are increased. Therefore, the solder material composition has a great influence on the brazing temperature, wettability, etc.

The component ratios (mass fraction, %) of the two solder materials are prepared as 79.5:5.5:10:5 and 70:15:10:5 for copper: tin: titanium: nickel, respectively, which will be called Cu79.5Ti10Sn5.5Ni5 and Cu70Sn15Ti10Ni5 respectively. , the two components were ball-milled and mixed for vacuum brazing diamond testing. The process is as follows: clean the Q235 steel substrate and diamond surface with acetone before vacuum brazing, place the CuSnTiNi solder on the surface of the steel substrate, and then arrange diamonds on the solder. The abrasive grains were heated to 1050, 1040, and 1030°C respectively, kept for 5 minutes, and then cooled in the furnace to below 100°C and taken out. The vacuum degree was less than 0.001 Pa. 300-mesh micro-powder diamond was brazed and used for X-ray diffraction.

The macroscopic morphology of vacuum brazing diamond using CuSnTiNi solder with two proportions of materials and holding the temperature at 1040°C for 5 minutes can be seen. Although the Cu79.5Sn5.5Ti10Ni5 solder is not fully melted, it has a certain climb on the diamond surface. When the tin content increases to 15%, the solder structure is uniform, indicating that the solder melts relatively well. Combining the Cu-Sn phase diagram, it can be seen that as the tin (melting point 231.9°C) content increases, the melting point almost always decreases, so when When the tin content increases, the melting point of the alloy decreases, but too much tin will reduce the performance of the tool, so the tin content must be controlled within a certain range. When the vacuum brazing temperature is 1030°C, the two solders do not melt well. The brazing filler metal can melt at 1050°C for brazing, but the temperature is too high, and the melting point of the filler metal is lowered after high-temperature alloying, so the flow is heavier. Too high diamond exposure is not conducive to the holding strength of the diamond, and it will also have a negative impact on the performance of the diamond. Damage, so this article focuses on the analysis of Cu70Sn15T10Ni5 diamond brazing under 1040℃ insulation for 5mim. The solder material is referred to as CuSnTiNi.
(1) Cu, Sn, Ti, and Ni elemental metal powders are ball-milled and mixed to make solder. It can achieve good wetting of diamond and achieve high-strength connection of diamond under the condition of 1040°C for 5 minutes.
(2) CuSnTiNi mixed metal powder is used to vacuum braze diamond, which causes less thermal damage to diamond and forms discontinuous and irregular TiC at the interface between diamond and brazing material.
(3) Adding an appropriate amount of Ni element to CuSnTi will help improve the hardness of the brazing layer. The microhardness reaches 130~180HV0.1, which is about 40%~45% higher than CuSnTi.