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Production Process Of Vacuum Brazed Diamond Saw Blade

How to improve the holding power of diamond by the metal matrix has always been an important direction of research. Among them, the most commonly used method is to coat the diamond surface with Ti, Cr and other metals. Although diamond plating can effectively prevent thermal damage to diamonds and improve the holding power of diamonds in the matrix, a large amount of practice has shown that its effect is not ideal.

Although brazed diamond tools have a large exposure height and holding force, their current applications are limited to the manufacture of single-layer diamond abrasive tools due to limitations of the brazing process itself. Since after the single layer of abrasive is consumed, there is no subsequent replenishment of abrasive, which limits the further improvement of the service life. For this reason, it has become a research topic for scientific and technological workers to produce diamond tool products that not only have the high holding power of single-layer brazed diamond tools, but also have the long life and easy cutting of sintered diamond tools.

In this study, CuFe-based formula was used, and the diamond abrasive was vacuum brazed to successfully produce a sintered diamond saw blade with vacuum brazing effect. This kind of saw blade was defined as a multi-layer brazed diamond saw blade. Through comparative tests, proved its superiority.

1 Test materials and process plan

1.1 Diamond surface vacuum brazing metallization treatment

Test materials and equipment: Ni-Cr alloy solder; certain alloy powder A (-300 mesh); Yellow River Cyclone HHD90, 40/45 diamond; $15mm, 10mm high 45″ steel cylinder; vacuum furnace; hot press sintering Machine etc.

The test plan is as follows:

1)Brazing diamond on a 45″ steel cylinder: Before vacuum brazing, degrease and decontaminate the abrasive grains and the surface of the base body, place the brazing filler metal on the end face of the base body, and then arrange the diamond abrasive grains. Place the sample Put it into a vacuum furnace and heat it to the brazing temperature and keep it warm for a suitable time. Finally, it is cooled to room temperature in the furnace. The results are shown in Figure 1.

Figure 1 Diluted brazing filler metal A-Ni based diamond brazing

2)Pre-brazing metallization of the surface of diamond abrasive grains: The author found through a large number of experiments that brazing diamonds with Ni-Cr alloy alone will cause a sharp decrease in diamond strength. Therefore, in this experiment, a certain proportion of A alloy powder was used to dilute the Ni-Cr alloy The mixed solder is defined as ANi-based solder, and the diamond is brazed with A-Ni-based solder. The results are shown in Figure 2, and the diamond is defined as pre-brazed diamond.

Figure 2 Morphology of A-Ni based brazed diamond

1.2 Manufacturing of multi-layer brazed diamond saw blades

Using unplated, titanium-plated and pre-brazed metallized diamond as abrasives and Fe-Cu based matrix formula, a b350 mm diamond saw blade was made, and a comparative cutting test was conducted. The cutting object was No. 635 granite plate.

2 test results

2.1 Diluted brazing diamond

The dilution of Ni-Cr solder by A alloy does not change the properties of the Ni-Cr solder itself, or the impact is too small to change the properties of the solder. It is feasible for A alloy to dilute the solder.

Ni-Cr alloy brazing material added with alloy A has better vacuum brazing effect on diamond. A-Ni brazing filler metal is dispersed on the diamond surface in the form of small spherical particles, and these small balls produce a better vacuum brazing connection to the diamond. The active element Cr in the solder alloy segregates at the interface and reacts with diamond to form the corresponding Cr carbide. Through the transition effect of Cr carbide, the wetting of the solder alloy to diamond is improved. This chemical reaction wetting mechanism causes the solder alloy to wet and climb on the diamond surface.

In addition to the chemical bonding force and metallurgical bonding force, the metal matrix’s holding force on diamond also has the effect of mechanical encrusting force. The pre-brazed diamond has many spherical and band-like tentacles of different sizes and shapes “growing” on the surface. The bonding strength between these tentacles and diamond is greater, making the relative surface area of diamond larger. Such diamonds will firmly grasp the surrounding matrix in the matrix, improving the matrix’s holding power of diamonds.

3 Comparison between multi-layer brazed diamond saw blades and titanium-coated and uncoated diamond saw blades

Three comparative test saw blades were made using uncoated diamond, titanium-coated diamond and pre-brazed diamond under the same other conditions. Use the TLJQ-400 sawing comparison test machine to saw granite slabs. In the process of cutting granite slabs, the speed of the three saw blades will fluctuate due to the wear and tear of the diamond. However, the sharpness of multi-layer brazed diamond saw blades is generally better than that of titanium-coated diamond saw blades and non-coated diamond chips. The sharpness is improved by 10% and 22.3% compared with titanium-coated diamond saw blades and non-coated diamond chips respectively. %, and the service life is slightly improved. Generally, a saw blade with good sharpness will make a quiet and crisp sound when cutting a board, while a saw blade with poor sharpness will make a loud and dull sound. In addition, the multi-layer brazed diamond saw blade has a higher degree of diamond exposure, which is significantly better than the other two diamond blades, and the tailing phenomenon occurs when the blade rotates in the opposite direction.

4 Conclusion on Vacuum Brazed Diamond Saw Blades

1) Alloy A does not have any adverse effects on the Ni-Cr alloy brazing unit. The Ni-Cr alloy brazing material added with Alloy A can still maintain excellent climbing wetting ability for diamond.

2) Adding Alloy A to the Ni-Cr alloy brazing material for brazing diamond can not only obtain surface-brazed diamond, but also effectively prevent the excessive decrease in the static pressure strength of the diamond, making the diamond have metallization properties, which can reduce the friction between the diamond and the metal tire. The interface energy between bodies.

3) For diamonds brazed with Ni-Cr alloy solder added with Alloy A, the wetting ability of the matrix to the brazed diamond is significantly improved, and the holding power of the diamond is significantly improved. The test found that the Ni content around the brazed diamond is relatively high. High, migration of Ni element may have occurred.