TW593769B - Plasma polishing method for titanium and titanium alloy products - Google Patents

Abstract

A plasma polishing method for titanium and titanium alloy products comprises: mounting a to-be-polished titanium or titanium alloy product in an electrolyte solution based on ammonium (NH4+) ions; and generating an air gap by using a d.c. voltage output to cause the electrolyte solution on the periphery of the to-be-polished article working as a positive electrode to undergo a instant vaporization due to a high electric potential difference. Such a continuous air gap will form a wrapping air film on the surface of the to-be-polished article, in which the vaporized particles in the air film form a discharge plasma due to dissociation by the high voltage, and the protruded portions on the surface of the to-be-polished article are flattened by the discharge plasma, thereby forming a mirror-like smooth surface and achieving the objective of polishing.

Description

593769 V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to a method for polishing titanium and titanium alloy products, and particularly to a method for polishing titanium and titanium alloy products by using a plasma. [Prior technology] Titanium and titanium alloys are widely used in various fields because they are lightweight, high strength, excellent corrosion resistance, and do not cause allergies to human skin. Titanium has mechanical properties such as high relative strength (tensile / density), high tensile strength, fatigue resistance, impact resistance, and high heat resistance, so it has been used in aerospace industry, sports equipment, bicycle parts, golf Ball heads, glasses and many other livelihood products. In addition, titanium and titanium alloys do not cause allergic reactions in human skin, so they can replace nickel or nickel alloy products that previously caused itchy or dermatitis skin. In addition, titanium and titanium alloys can be used in medical equipment, such as tweezers, and as materials for biological implants, such as bone fixation plates, screws, and spinal cages. Because of the wide application of Chin metals and alloys, the processing of Chin materials has also received increasing attention. The polishing process can handle the rough surface formed by the processing and give the product a better texture. Therefore, it is the entire titanium metal and An indispensable machining program in the processing of titanium alloys. The conventional polishing methods of titanium metal and titanium alloy can be divided into three types, namely mechanical polishing method, chemical polishing method and electrolytic polishing method, but each has its limitations and disadvantages. The conventional mechanical polishing method is labor-intensive and is more suitable for flat materials. For non-planar materials, there will be dead corners that cannot be polished. In addition, titanium is

593769 V. Description of the invention (2) An active metal that undergoes mirror polishing treatment for a period of time, and the surface properties of the mirror surface will oxidize again. Therefore, Tokui Fukai et al. In Japanese patent JP 4 0 4 1 6 5 6 discloses a technique using heat treatment , To prevent the phenomenon of mirror surface properties oxidation. However, the temperature used in this heat treatment method is quite high (300 ~ 800). At the same time, it is necessary to control the polishing in a high vacuum (10-3 t0) rr. In addition, Hirata Shuichi Et al. In Japanese patent jP617〇721 discloses another technique of adding an oxidizing agent during polishing and grinding, the purpose of which is to form a surface oxide layer on the surface of titanium metal to prevent the abrasive from being embedded and mixed into the surface of titanium metal. ≫ To form an abrasive layer and improve the polishing effect. However, this method is still more suitable for processing flat plates. For products with three-dimensional curved surfaces or holes, there are blind spots and difficulties in processing. Xilianlian Hydrofluoric Acid The chemical polishing method known for environmentally friendly products, such as a hydrofluoric acid one-stage complete acid, is used to treat titanium metal using an acidic solution, such as the use of nitric acid, sulfuric acid, 4 ° as disclosed in Lee SU1 7 1 5887. % Acetic acid and water polishing mixed in a ratio of 25 ~ 30%: 40 ~ 45%: 2 ~ 5%: 25 ~ 28%. In addition, Matsuo Tomoyuki et al. Disclosed a two-stage chemistry in Japanese patent Jp4088l78. Polishing method First, the titanium product is mixed with phosphoric acid and acetic acid, and the mixture is heated to 5 叱 for the first polishing, and then the hydrogen peroxide and hydrofluoric acid are mixed in the second mixing ratio of 7.1. It can be seen that most of the chemical polishing methods use high-concentration solutions, which will cause problems for the recovery or treatment of waste acid liquid, and may also cause adverse effects. In addition, for the titanium finished polishing, because of the material There are differences in the etching rate between different phases of the microscopic surface (Phase) or between the grains (Grain) and the grain boundary (Grain boundary), which will make it difficult for the finished product and surface to achieve a bright and smooth effect.

Page 559769 Description of the invention (3) As for the electrolytic polishing method, like the chemical polishing method, it is also necessary to use a high concentration acid solution as the electrolyte, such as Uradoren Mlhairc) buitsuchl Shany et al. ^ Japanese Patent JP 5 6 0 1 The aqueous solution made of sulfuric acid, nitric acid and nitrogen acid and mixed with surfactants as disclosed in 6 7 0 is used as the electrolytic polishing solution of titanium and titanium alloys. This method still has high toxicity, high risk and difficult process management. And various problems such as waste liquid pollution. Therefore, from the above, it can be known that there are limitations in processing technology in the conventional technology and other shortcomings that are not easy to handle. Therefore, if a method can be provided which is simple, safe, safe, and excellent in processed products, Will reduce the cost of the polishing process, and further improve the availability of titanium products. [Summary of the Invention] One of the objects of the present invention is to provide a fast and cheap polishing method, so that titanium and titanium alloy products can obtain a clean and bright surface, and give the finished product a better texture. Another object of the present invention is to improve oil removal and rust removal simultaneously, so as to increase efficiency, reduce inconvenience and waste. Another object of the present invention is to provide no reduction of risks in the manufacturing process, and at the same time reduce the problem. Another object of the present invention that can save the preparation of the solution is to mention the shape of the Chin products, including titanium products having curved and other titanium products, and the process of degreasing, cleaning, and polishing in the well-known polishing technology of polishing. Into the toxic and non-polluting electrolytic solution, the concentration of the electrolyte will not cause environmental protection costs. Provides a quick and easy method for polishing any surface 'hollow tube and three-dimensional shape The surface of the polished object is free of any chemicals

Page 6 593769 V. Description of the invention (4) Quality pollution. The invention relates to a method for polishing the surface of a person with a plasma polishing method. This plasma polishing method is based on an electrolytic solution with a total concentration of industrial titanium and gold ions (N Η /). It is made of titanium and titanium alloy, σ 1 5% 'and recorded in the electrolytic solution. The output of the DC voltage makes the positive pole °° waiting, and the electrolytic solution placed on the object to be polished evaporates instantly due to the high potential difference to generate a bubble bag (around the Ai light object, and then a continuous air film is formed. 1 The surface of the object to be polished, at the same time, the surface of the object to be polished is electrochemically oxidized by R s. When the surname engraving rate and the oxidation rate reach the optimal ratio of two, use = f: = the surface of the object to produce an excellent polishing effect. In addition, the high potential difference passes through the formation of an electric field between the surface of the object to be polished and the air film, 'relative to the surrounding area where the local protrusions' has a larger electric field at the local protrusions on the surface of the polished object, so the plasma etching rate there is also Larger. As the processing time increases, the roughness of the surface of the object to be polished will decrease, and a completely flat polished surface will eventually be achieved. Therefore, as long as the object to be polished is a conductor, such as hafnium or titanium alloy products, and Electrolytic polishing can be performed in the electrolyte. In addition, regardless of the shape of the object to be polished, such as curved three-dimensional products or hollow tubular products, as long as it can be immersed in the electrolyte, the outer and inner surfaces can be polished. Polishing. The following will further illustrate the present invention with specific examples. The following examples are dry: The book is not intended to limit the scope of the present invention, anyone familiar with this toilet; sharp, fT is outside the spirit and scope of the present invention Within the scope of the invention, the scope of protection of the invention shall be regarded as the scope of the patent application attached.

$ 7 页 593769 V. Description of the Invention (5) [Embodiment] The first embodiment of the example is a 150x150x3 mm pure titanium flat-handled rabbit, &. Ammonium hydroxide aqueous solution, and the working current and the formula II are added to prepare 8% of chlorosulfonium to be 2 0 8 to 380V, and the heating temperature of the electrolyte is 70 to 9 m before the working voltage and relative reflectance are calculated. The results are shown in Table—shown. In the middle, the surface roughness is shown by the phase roughness (Ra) measured by the stylus surface roughness meter: The relative reflectance is measured as follows. The relative reflectance (%) = (gloss measurement value / repetition) Χ100%] value / Measurement value of silver mirror 1 (considered as 100% reflection) As can be seen from Table 1, as the polishing time increases, the relative reflectance decreases. The speed of determination increases, and the electro-polishing throws for 7 minutes. From the original 0.7M m to 0.1U m, and the relative reflectance from 91%. It can be seen that the present invention can achieve a good polishing effect under fairly mild processing conditions. Specific Example 2 Ti-6A1_4V The titanium alloy golf head is a test sample. Its dimensions are 130mm in length, 90mm in width, and 54mm in height. It is a hollow cast body. It is formulated with a mixture of 0.5 to 5% chlorinated chloride and 0.5 to 5% gasified ammonium. The solution is an electrolytic solution, and the working current density is set to 0.42A / cm2, the working voltage is set to 300 to 420V, and the heating temperature of the electrolytic solution is 60 to 95 ° C. Plasma polishing is performed under the foregoing conditions. Because of this, specific

Page 8 593769 V. Description of the invention (6) The sample in the embodiment is a three-dimensional arc, so it is difficult to measure the change in surface roughness. It is only expressed by the relative reflectance of the fixed position measured by gloss measurement, and the relative reflectance of The measurement and calculation are the same as those in Example 1. The results are shown in Table 2. Table 2 shows that as the polishing time increases, the relative reflectance increases rapidly. After 5 minutes of plasma polishing, the relative reflectance of the polished sample can be greatly improved, regardless of the voltage of 3 8 0 V or 4 2 0 V. It can be seen that the plasma polishing method of the present invention can also provide excellent polishing results for objects with three-dimensional shapes such as curved surfaces. Specific Example 3 A titanium alloy screw of T i-6 A and 4 V is used as a test sample. This screw is a medical human implant. Its size is 10 mm in length and 6 mm in diameter. 1A / cm2 First prepare 0.5 ~ 5 fir ammonium chloride, 0.5 ~ 5% ammonium sulfate and 0.5 ~ 5% ammonium chloride mixed solution as the electrolyte, and set the working current density to 0. 1A / cm2 The operating voltage is set to 2 0 ~ 3 2 0 V, the heating temperature of the electrolyte is 7 5 ~ 9 6 ° C, and the plasma polishing is performed under the aforementioned conditions. Because the surface roughness and relative reflectance of the screw sample are difficult to measure, the metallographic photo of an optical microscope containing two sets of threads before polishing and the metallographic photo after polishing at the same position for 1 minute (as shown in the first figure and the second (Shown). The photos in the first and second pictures show that the polished burrs have been removed, and the surface has become very bright. In addition, the processing lines in the grooves have been removed and leveled. From the above description and specific examples, it can be found that the plasma polishing method of titanium and titanium alloy products of the present invention can completely improve the shortcomings of the conventional technology, and the process is simple, applicable to titanium products of any shape, and improving the safety of operation. and

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593769 A simple illustration of the screw after the light; head The first picture is a group of screw optical microscope metallographic photos of Ti-6A and 4V titanium alloy screws before and after plasma polishing. The first image (A) is an optical microscope metallographic photograph of the plasma polishing grain, and the first image (B) is the metallographic image of the threaded optical microscope at the same position of the plasma polishing. The second picture is another group of metallographic pictures of threaded light microscope of Ti-6A 1-4V titanium alloy screw before and after plasma polishing. The second image (A) is a metallographic picture of the screw groove optical microscope before plasma polishing, and the second image (B) is the metallographic picture of the screw groove optical microscope in the same position after the plasma polishing.

Page 11 593769 Table 1. Surface roughness and relative reflectance of the polished sample obtained in Example 1 of the present invention. Polishing time (min) Surface roughness (μπι) Relative reflectance (%) 〇 (Before polishing) 0.71 34 0.25 0.67 36 0.5 0.61 44 1 0.49 53 2 0.37 69 3 0.22 82 5 0.13 90 7 0.11 91 593769 Table 2. Relative reflectance of the polished sample obtained in the specific embodiment 2 of the present invention. Polishing time (min) Relative reflectance (%) Voltage 3 80V Voltage 420V 〇 (Before polishing) 58 59 0.5 61 70 1 70 78 2 79 87 3 82 88 5 84 8 8 7 83 86

Claims (1)

593769 ^ Application scope: 1. A plasma polishing method for titanium and titanium alloy products, comprising at least the following steps: (a) preparing an electrolyte containing ammonium ions (NH4 +); (b) electrolyzing the electrolyte The temperature of the liquid is maintained in the range of 60 to 98 ° C; (c) the object to be polished is immersed in the electrolyte; (d) a DC positive voltage of 2 1 0 to 4 2 0 V is applied to the object to be polished Polishing with a discharge plasma; and (e) After polishing is completed, the polished product is taken out. 2. The plasma polishing method for titanium and titanium alloy products as described in item 1 of the scope of the patent application, wherein the concentration of the electrolyte containing ammonium ions is 1-15%. 3. The plasma polishing method for titanium and titanium alloy products according to item 1 of the scope of the patent application, wherein the electrolytic solution containing ammonium ions includes an ammonium chloride solution. 4. The plasma polishing method for titanium and titanium alloy products according to item 1 of the scope of the patent application, wherein the electrolyte containing ammonium ions comprises an ammonium fluoride solution. 5. The plasma polishing method for titanium and titanium alloy products according to item 1 of the scope of the patent application, wherein the electrolytic solution containing ammonium ions includes an ammonium sulfate solution. 6. The plasma polishing method for titanium and titanium alloy products described in item 1 of the scope of the patent application, wherein the electrolyte containing ammonium ions is a 1 to 8% ammonium chloride solution. Page 12 593769 VI. Patent Application Range 7. The plasma polishing method for titanium and titanium alloy products as described in item 6 of the patent application range, wherein the temperature of the electrolyte is maintained in the range of 70 to 98 ° C. Inside. 8. The plasma polishing method for titanium and titanium alloy products as described in item 6 of the scope of the patent application, wherein the DC positive voltage applied to the object to be polished is 2 0 0 to 3 8 0 V. 9. The plasma polishing method for titanium and titanium alloy products as described in item 7 of the scope of the patent application, wherein the DC positive voltage applied to the object to be polished is 2 0 0 to 3 8 0 V. 1〇. The plasma polishing method for titanium and titanium alloy products described in item 1 of the scope of the patent application, wherein the electrolyte containing ammonium ions is 0.5 ~ 5% ammonium chloride solution and 0.5 ~ 5 % Ammonium fluoride solution. 11. The plasma polishing method for titanium and titanium alloy products as described in item 10 of the scope of the patent application, wherein the temperature of the electrolyte is maintained in the range of 60 to 95 ° C. 1 2. The plasma polishing method for titanium and titanium alloy products as described in item 10 of the scope of patent application, wherein the DC positive voltage applied to the object to be polished is 300 ~ 420V ° 1 3. The plasma polishing method for titanium and titanium alloy products as described in item 11 of the scope of the patent application, wherein the DC positive voltage applied to the object to be polished is 300 ~ 420V. Page 13 593769 VI. Application for patent scope 1 4. The plasma polishing method for titanium and titanium alloy products described in item 1 of the scope of patent application, wherein the electrolyte containing ammonium ions is 0.5 to 5% chlorine Ammonium hydroxide solution, a mixed solution of 0.5-55% sulfuric acid solution and 0.5-5 ammonium ammonium solution. 15. The plasma polishing method for titanium and titanium alloy products as described in item 14 of the scope of the patent application, wherein the temperature of the electrolyte is maintained in the range of 75 to 96 ° C. 16. The plasma polishing method for titanium and titanium alloy products as described in item 14 of the scope of patent application, wherein the positive DC voltage applied to the object to be polished is 210 ~ 320V. 17. The plasma polishing method for titanium and titanium alloy products as described in item 15 of the scope of the patent application, wherein the positive DC voltage applied to the object to be polished is 210 ~ 320V. 1 8. The plasma polishing method for titanium and titanium alloy products according to item 1 of the scope of the patent application, wherein the object to be polished is a three-dimensional article having a curved surface. 19. The plasma polishing method for titanium and titanium alloy products as described in item 1 of the scope of the patent application, wherein the object to be polished is a hollow tubular object. 20. — An article made using the plasma polishing method for titanium and titanium alloy products as described in item 1 of the scope of the patent application. Page 14