Composite gold-plated diamond and production process thereof

Abstract

The application discloses a production process of composite plated diamond, which comprises a surface impurity removing process, a micro-evaporation titanium plating process, a sharp-end discharge rolling nickel spike plating process and a chemical nickel spike ball plating process; after the surface is wrapped with titanium, electroplating and chemical plating are carried out to form thick and strong nickel spikes and nickel balls, the holding force between the diamond and the binder is increased, and the diamond / CBN is prevented from falling off; the obtained composite plated diamond can meet the use of resin binder and the use of ceramic and metal binder, the interface bonding force between the diamond / CBN and the binder is improved, and the service life of the grinding wheel made of the ceramic binder is increased by more than 15% without affecting the machining efficiency.

Description

Technical Field

[0001] This invention relates to the application of diamond / CBN abrasives in resin, ceramics, and metal binders, and particularly to a composite diamond-plated abrasive and its production process. Background Technology

[0002] Diamond / CBN is often used as an abrasive due to its high hardness, high strength, and good wear resistance; however, because the bond between diamond / CBN and the binder is not strong, its surface needs to be treated to increase the holding force between it and the binder.

[0003] During the grinding process, diamond / CBN may detach or its mechanical properties may deteriorate, severely affecting its service life. To reduce the detachment rate of diamond / CBN, surface nickel plating is often used to increase the adhesion between the diamond / CBN and the binder.

[0004] Currently, in China, rough nickel balls are often plated onto the surface of diamond / CBN. The contact between the ball and the binder is surface contact, which results in insufficient holding power and easy detachment.

[0005] In foreign countries, rough nickel spikes are often plated on the surface of diamond / CBN to increase the holding force with the binder; however, nickel-plated diamond / CBN is only suitable for molds with resin binders. In hot-pressed sintered ceramic and metal binders, the nickel spikes are destroyed and cannot improve the holding force with ceramic and metal binders.

[0006] Metal plating typically employs methods such as chemical plating and composite plating.

[0007] Chemical plating involves forming nickel-phosphorus alloy particles on the surface of diamond / CBN through a redox reaction, which modifies the polycrystalline diamond to be polar and makes it easier to bond with the binder; however, the nickel-phosphorus alloy and the surface of polycrystalline diamond are prone to hydrogen embrittlement.

[0008] Composite plating combines chemical plating and electroplating. The purpose of electroplating is to increase the nickel content and coating thickness, filling gaps in the chemical plating layer. Electroplating produces polarization. Initially, during electroplating, the electrolysis rate is greater than the plating rate, resulting in rapid coating decomposition. Later, during electroplating, the plating rate is greater than the electrolysis rate, leading to rapid coating growth. However, if not properly controlled, it can easily cause over-electrolysis of the chemical plating layer, resulting in incomplete plating or uneven coating thickness. When bonding with the binder, insufficient holding force can lead to cracking. If the binder erodes the diamond / CBN surface, the instantaneous high temperature during high-speed cutting or grinding causes the difference in thermal expansion coefficients between the metal and diamond / CBN, making cracking easy. Diamond / CBN may detach, leaving the binder only bonded to the metal shell, which can then accumulate chips, forming a pseudo-abrasive and reducing processing capability. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the existing defects and provide a composite diamond plating process and its production process. The process involves coating the surface with titanium, followed by electroplating and chemical plating to form robust nickel spikes and nickel balls, which increases the holding force between the nickel and the binder and prevents the diamond / CBN from falling off. This process satisfies the requirements of both resin binders and ceramic and metal binders, while also improving the interfacial bonding force between the diamond / CBN and the binder. This can effectively solve the problems in the background art.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a composite diamond plating production process, including a surface impurity removal process, a micro-evaporation titanium plating process, a tip discharge barrel plating nickel spike process, and a chemical nickel spike ball plating process.

[0011] The surface impurity removal process includes soaking in sulfuric acid solution, boiling, filtering, and drying.

[0012] The micro-evaporation titanium plating process includes preparing a mixture of diamond / CBN and titanium powder in proportion, evaporating and plating titanium at 500℃-775℃ for 0.5-1.5h, cooling and sieving to obtain titanium-plated diamond / CBN;

[0013] The tip-discharge barrel plating process for nickel spikes includes a plating solution and barrel plating of titanium-plated diamond / CBN in a bottle to obtain diamond / CBN with nickel spikes.

[0014] The electroless nickel-plated spike process includes sensitizing, activating, and reducing the diamond / CBN spikes to be plated, followed by electroless plating by immersion in a plating solution to obtain the diamond / CBN spikes with nickel plating.

[0015] As a preferred embodiment of the present invention, the plating solution of the tip discharge barrel plating nickel spike process includes 250 g / L nickel sulfate, 35 g / L nickel chloride, 30-40 g / L boric acid, 0.2-0.6 g / L hexadecyl ammonium bromide, pH value of 5-5.5, barrel plating speed of 10-25 r / min, temperature of 80℃-85℃, voltage of 5-10V, current of 1-5A gradually increased and then decreased, and barrel plating time of 6-18h.

[0016] As a preferred technical solution of the present invention, the sensitization, activation and reduction in the electroless nickel plating process are as follows: the diamond / CBN with nickel plating is added to a 0.5 g / L stannous chloride solution for sensitization for 15 min and washed twice with water; then it is added to a 0.5 g / L palladium chloride solution for activation for 30 min and washed with water; finally, it is added to a 25 g / L sodium hypophosphite solution for reduction for 30 min.

[0017] As a preferred embodiment of the present invention, the plating solution in the electroless nickel plating process comprises 40 g / L nickel sulfate, 15 g / L sodium citrate, 23 g / L sodium acetate, 56 g / L sodium hypophosphite, 0.2 g / L sodium thiosulfate, and 0.1 g / L cetyl ammonium bromide; the plating solution temperature is 80-85℃; the pH is 5-5.5; and the plating time is 1-6 hours.

[0018] The present invention also provides a composite diamond-plated diamond produced using the above-described production process.

[0019] Compared with the prior art, the beneficial effects of the present invention are: the composite diamond plating and its production process adopt the method of boiling diamond with dilute sulfuric acid, which effectively removes impurities on its surface. Compared with nitric acid and hydrochloric acid, sulfuric acid has stronger permeability. At the same time, polycrystalline diamond is unstable at room temperature and pressure and will spontaneously and slowly transform into graphite phase. Sulfuric acid has good wettability to graphite, thereby ensuring the cleanliness of the diamond surface.

[0020] By employing a micro-evaporation titanium plating method, TiC is formed on the surface of diamond / CBN, exhibiting high interfacial bonding strength. After TiC encapsulates diamond / CBN, the superior thermal conductivity of titanium compared to diamond / CBN reduces the probability of diamond graphitization and prevents CBN from reverting to HBN. Simultaneously, titanium possesses good resistance to electrolytic corrosion, which is beneficial for discharge at the barrel plating tip, forming nickel spikes at the diamond edges and preventing electrolytic plating defects on the diamond / CBN surface.

[0021] The tip discharge nickel spike plating process is adopted, which utilizes the tip discharge effect to preferentially grow nickel spikes at the edges of diamond / CBN.

[0022] A chemical nickel spike ball plating process is employed, in which nickel spikes are chemically plated onto the diamond / CBN surface to be formed. Since the surface area of ​​diamond / CBN is larger than that of nickel spikes, by controlling the reduction rate, nickel balls are preferentially grown on the diamond / CBN surface. At the same time, the cross-sectional diameter of the nickel spikes is increased, resulting in diamond / CBN with nickel spike balls. During the hot pressing process, this effectively reduces the probability of nickel spike breakage, allowing the nickel spikes to embed into the binder and effectively improving the holding force.

[0023] During use, by adjusting the ratio of tip discharge nickel plating and electroless nickel plating ball processes, the ratio of nickel spikes to nickel balls can be changed, balancing production costs and the holding force requirements of diamond / CBN and the binder, thus meeting the diverse application needs of resin, ceramic, and metal binder abrasives.

[0024] Using this process for nickel plating, the titanium powder, barrel plating solution, and chemical plating solution involved can be reused, there is no heavy metal emission, and production costs are significantly reduced.

[0025] The composite diamond-plated ceramic bond grinding wheels produced using this process have a service life increased by more than 15% without affecting processing efficiency. Attached Figure Description

[0026] Figure 1 This is the product after tip discharge nickel plating following the invention;

[0027] Figure 2 This is the product after chemically plated nickel spikes according to the present invention;

[0028] Figure 3 This is an electron microscope image of the monomer after the electroless nickel plating of the spiked balls of this invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1:

[0031] This invention provides a technical solution: a composite diamond plating process and its production process, including a surface impurity removal process, a micro-evaporation titanium plating process, a tip discharge barrel plating process for nickel spikes, and a chemical nickel spike ball plating process;

[0032] (1) Diamond / CBN with a particle size of 40-500μm is boiled with 10% sulfuric acid for 30 minutes to remove impurities and then dried for later use.

[0033] (2) Diamond / CBN and titanium powder are mixed evenly in a mass ratio of 4:1-3. The titanium powder has a particle size of 50-280μm. The mixture is placed in a vacuum micro-evaporation titanium plating chamber and evaporated at 775℃ for 1h. After cooling, the mixture is sieved to obtain titanium-plated diamond / CBN.

[0034] (3) Load diamond / CBN into a barrel plating bottle with a loading capacity of 200-600g. The plating solution consists of 250g / L nickel sulfate, 35g / L nickel chloride, 30-40g / L boric acid, and 0.2-0.6g / L cetyl ammonium bromide. The rotation speed is 10-25r / min, the pH is controlled at 5-5.5, the temperature is 80-85℃, the voltage is 5-10V, and the current is 1-5A, which is gradually increased and then decreased. The barrel plating time is controlled at 6-18h according to the required length of the nickel spikes to obtain nickel-plated diamond / CBN.

[0035] (4) Wash the nickel-plated diamond / CBN with water 3-5 times and set aside;

[0036] (5) Add diamond / CBN to a 0.5 g / L stannous chloride solution, sensitize for 15 min, and wash twice with water; add to a 0.5 g / L palladium chloride solution, activate for 30 min, and wash with water; add to a 25 g / L sodium hypophosphite solution, and reduce for 30 min.

[0037] (6) Perform electroless nickel plating. The plating solution consists of 40 g / L nickel sulfate, 15 g / L sodium citrate, 23 g / L sodium acetate, 56 g / L sodium hypophosphite, 0.2 g / L sodium thiosulfate, and 0.1 g / L cetyl ammonium bromide. The plating solution temperature is 80-85℃, and the pH is 5-5.5. The nickel plating time is controlled between 1-6 hours depending on the weight gain.

[0038] (7) Wash with water 3 times and dry to obtain diamond / CBN with nickel-plated spikes. The weight gain can be controlled at 20-70%.

[0039] The control group experiment is as follows:

[0040]

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite diamond plating production process, characterized in that, This includes surface impurity removal processes, micro-evaporation titanium plating processes, tip discharge barrel plating of nickel spikes processes, and chemical nickel plating of spike balls processes; The surface impurity removal process includes soaking, boiling, filtering, and drying diamond / CBN particles with a size of 40-500μm in sulfuric acid solution; The micro-evaporation titanium plating process includes: mixing diamond / CBN and titanium powder in a mass ratio of 4:3 to obtain a uniform mixture with titanium powder particle size of 50-280μm; placing the mixture in a vacuum micro-evaporation titanium plating chamber; heating the mixture at a temperature of 500℃-775℃; evaporating the mixture for 0.5-1.5 hours; cooling the mixture and then sieving it to obtain titanium-plated diamond / CBN. The tip-discharge barrel plating process for nickel spikes includes a plating solution and barrel plating of titanium-plated diamond / CBN in a bottle to obtain diamond / CBN with nickel spikes. The electroless nickel-plated spike process includes sensitizing, activating, and reducing the diamond / CBN spikes to be plated, followed by electroless plating by immersion in a plating solution to obtain the diamond / CBN spikes with nickel plating.

2. The composite diamond-plated production process according to claim 1, characterized in that: The plating solution for the tip discharge barrel plating process for nickel spikes includes 250 g / L nickel sulfate, 35 g / L nickel chloride, 30-40 g / L boric acid, and 0.2-0.6 g / L hexadecyl ammonium bromide. The pH value is 5-5.5, the barrel plating speed is 10-25 r / min, the temperature is 80℃-85℃, the voltage is 5-10V, the current is 1-5A gradually increased and then decreased, and the barrel plating time is 6-18h.

3. The composite diamond-plated production process according to claim 1, characterized in that: The sensitization, activation, and reduction processes in the electroless nickel plating process are as follows: the diamond / CBN plated with nickel is added to a 0.5 g / L stannous chloride solution for sensitization for 15 min, followed by two water washes; then it is added to a 0.5 g / L palladium chloride solution for activation for 30 min, followed by water washes. Add to a 25 g / L sodium hypophosphite solution and reduce for 30 min.

4. The composite diamond-plated production process according to claim 1, characterized in that: The electroless nickel plating process for spiked balls comprises a plating solution of 40 g / L nickel sulfate, 15 g / L sodium citrate, 23 g / L sodium acetate, 56 g / L sodium hypophosphite, 0.2 g / L sodium thiosulfate, and 0.1 g / L cetyl ammonium bromide; the plating solution temperature is 80-85℃; the pH is 5-5.5; and the plating time is 1-6 hours.

5. Composite diamond-plated diamond produced using the production process described in any one of claims 1-4.

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