TWI605898B - Surface modification method of metallic workpiece - Google Patents

Description

Metal workpiece surface modification method

The invention relates to a method for modifying a surface of a workpiece, in particular to a method for modifying a surface of a metal workpiece.

In general, the metal workpiece can be modified to improve the material properties, so that the metal workpiece can be applied to different application fields, especially for metal workpieces whose surface is easy to generate oxidation reaction and generate oxide film. Surface modification technology More necessary to exist. Among them, the surface modification technology of stainless steel which is easy to oxidize and widely used in various fields is widely concerned by the industry.

At present, the surface modification is used to strengthen the material properties of stainless steel itself, but many technically difficult to overcome bottlenecks. For example, in order to increase the hardness of a stainless steel surface, a nitriding process is selected, and since one surface of the stainless steel forms an oxide layer due to oxidation, when a nitriding process is performed with a nitrogen-containing gas, the inclusion The nitrogen gas must first penetrate the oxide layer to further penetrate into a substrate layer, thus causing the nitriding process to be lengthy and not conducive to mass production.

In view of this, it is indeed necessary to develop a surface modification method of a metal workpiece to solve the aforementioned problems.

The metal workpiece surface modification method of the invention can reduce the time for the modified gas to infiltrate into the metal workpiece, and can increase the hardness of the surface of the metal workpiece.

The main object of the present invention is to provide a method for modifying a surface of a metal workpiece, comprising: impinging a metal workpiece having an oxide layer on a surface thereof, forming a nano grain structure at an impact portion of the metal workpiece, and removing the metal The oxide layer of the workpiece is exposed to reveal the nano-grain structure, and a modified gas penetrates the nano-grain structure and penetrates into the metal workpiece, so that the surface of the metal workpiece forms the nano-grain structure a hardened layer.

According to the nano grain structure of the metal workpiece, the modified gas can quickly penetrate the metal workpiece to reduce the infiltration time of the modified gas.

Referring to FIG. 1 , a method for modifying a surface of a metal workpiece according to the present invention includes “impacting a metal workpiece having an oxide layer on a surface” 10 , “removing the oxide layer of the metal workpiece” 20 and “modifying The gas penetrates the nanograin structure and penetrates into the metal workpiece "30".

Referring to Figures 1 and 2, first, in the step of "impacting a metal workpiece having an oxide layer on one surface" 10, a metal workpiece 200 is impacted by an impact device 100 to cause a metal workpiece 200 to be subjected to Forming a nano-grain structure at the impact, the metal workpiece 200 may be selected from a stainless steel or other metal of the Vostian system. In the embodiment, the impact device 100 includes a first chamber 110, an oscillator 120, and The plurality of fine particles 130 are preferably generated so as to generate ultrasonic waves and drive the fine particles 130 to vibrate, and the type thereof is not limited. In this embodiment, the vibration frequency of the oscillator 120 is 20 to 50 kHz, and the fine particles 130 may be selected according to the use condition, such as a magnetic bead, and the preferred particle diameter is selected from 0.8 to 4.5 mm. The device 120 is configured to oscillate the fine particles 130 to cause the fine particles 130 to bounce irregularly in the first chamber 110.

Referring to Figures 1, 2 and 4, in the step of "impacting a metal workpiece having an oxide layer on one surface" 10, the metal workpiece 200 is placed in the first chamber 110, and The vibrator 120 vibrates the fine particles 130 to impact the metal workpiece 200. Referring to FIGS. 4 and 5, in the embodiment, a surface 210 of the metal workpiece 200 has an oxide layer 220, and the fine particles 130 impact the The metal workpiece 200 is such that the metal workpiece 200 is formed with a nano-grain structure 240 at the impact.

Referring to FIGS. 4 and 5, in the present embodiment, the metal workpiece 200 has a base layer 230 that is in contact with the oxide layer 220. The oxide layer 220 is formed on the base layer 230 by the fine particles 130. The oxide layer 220 and the base layer 230 of the bead strike are the impacted portion of the metal workpiece 200. The nano-grain structure 240 formed by the impact portion penetrates the base layer 230 from the surface of the oxide layer 220. To change the surface grain structure of the base layer 230 where the base layer 230 and the oxide layer 220 meet.

Referring to FIGS. 2 and 5, in the embodiment, the fine particles 130 strike the metal workpiece 200 at a speed of 5 to 15 m/s, so that the impact of the metal workpiece 200 can be deepened from the oxide layer 220. a base layer 210 that interfaces with the base layer 210, and preferably has a depth of impact between 0.1 and 1 μm, and particularly 20 nm of the nano-grain structure 240 is formed at the impact, the nano-grain Structure 240 Those whose material grain size is less than 100 nm.

Referring to Figures 1, 3 and 6, in the step of "removing the oxide layer of the metal workpiece" 20, the oxide layer 220 of the metal workpiece 200 is removed to expose the substrate layer 210. The nanograin structure 240. In the present embodiment, the nano-grain structure 240 particularly refers to the surface grain structure of the base layer 210 where the base layer 210 and the oxide layer 220 meet, which are formed by impact changes.

Referring to Figures 1, 3 and 6, in the step of "removing the oxide layer of the metal workpiece" 20, the metal workpiece 200 is placed in a second chamber 310 of a reaction chamber 300. The oxide layer 220 of the metal workpiece 200 is removed by a de-oxidation layer fluid A1 to expose the nano-grain structure 240 located on the base layer 210. The nano-grain structure 240 is from the surface of the substrate layer 210. The depth of penetration is close to 20nm. In this embodiment, the deoxidizing layer fluid A1 is selected from a halogen fluid, and the deoxidizing layer fluid A1 may be selected from the group consisting of hydrogen chloride and nitrogen trifluoride, and the oxide layer 220 is removed by the deoxidizing layer fluid A1. It is 0.5 to 5 hours.

Referring to Figures 1, 3 and 7, in the step of "passing the nano-grain structure and infiltrating the metal workpiece with a modified gas", the step of removing the oxide layer 220 of the metal workpiece 200 is performed. Thereafter, the modified grain gas A2 penetrates the nano-grain structure 240 located in the base layer 210, and the modified gas A2 penetrates into the metal workpiece 200, so that the surface 210 of the metal workpiece 200 forms the surface. A hardened layer 250 of the rice grain structure 240. In the present embodiment, the base layer 230 has a permeable layer 230A infiltrated by the reforming gas A2. The permeable layer 230A and the nano-grain structure 240 constitute The hardened layer 250, preferably, has a thickness of 5 to 30 μm.

Referring to Figures 1, 3 and 7, in the present embodiment, the modified gas A2 is delivered to the second chamber 310 of the reaction chamber 300, the modified gas is selected from the group consisting of nitrogen-containing gas and carbon. a gas or a mixed gas containing carbon and nitrogen, wherein an operating temperature in the second chamber 310 is maintained between 350 and 550 degrees Celsius, so that the reforming gas A2 penetrates the nanograin structure 240 and penetrates into the The metal workpiece 200 is formed with the hardened layer 250, and the modified gas A2 penetrates the nanograin structure 240 and infiltrates into the metal workpiece for a period of 2 to 36 hours.

Please refer to FIGS. 1, 4 to 6, since the oxide layer 220 has been removed and the nanograin structure located in the base layer 210 is exposed before the metal workpiece 200 is modified with the reformed gas A2. 240, so when the modified gas A2 penetrates into the metal workpiece 200, the modified gas A2 can quickly penetrate the nano-grain structure 2 and infiltrate into the base layer 210 of the metal workpiece 220 to form the modified The permeable layer 230A and the hardened layer 250 of the nano-grain structure 240 reduce the processing time for modifying the metal workpiece 200 with the reformed gas A2.

In summary, the present invention utilizes the impact energy to change the grain structure of the metal workpiece 200, so that the impacted metal workpiece 200 can be increased by about 3 times due to the formation of the nano-grain structure 240 on the surface of the base layer 210. Surface hardness as compared to untreated metal workpieces, as shown in Figure 4. Moreover, due to the change of the grain structure on the surface of the metal workpiece 200, a chemical heat treatment such as carburizing, nitriding or carbonitriding may be further utilized, so that the metal workpiece 200 is ultimately caused by the gas element and the nanograin structure 240. The hardened layer 250 having a thickness of 5 to 30 μm is collectively formed, and in particular, the hardened layer 250 can be increased to a thickness of 20 to 30 μm.

In this way, in addition to improving the hardness through the change of the grain structure, the present invention can also effectively reduce the chemical heat treatment time, and further form the hardened layer 250 with a better thickness through the elemental infiltration and the nano grain structure to make the metal workpiece. Both the hardness and the wear resistance are improved, thereby prolonging the use margin and the life of the metal workpiece 200.

The scope of the present invention is defined by the scope of the appended claims, and any changes and modifications made by those skilled in the art without departing from the spirit and scope of the invention are within the scope of the present invention. .

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10‧‧‧A metal workpiece with one oxide layer on one surface

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20‧‧‧Remove the oxide layer of the metal workpiece

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30‧‧‧ penetrates the nano-grain structure with a modified gas and infiltrates the metal workpiece

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100‧‧‧ impact device

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110‧‧‧ first chamber

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120‧‧‧ oscillator

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130‧‧‧fine particles

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200‧‧‧Metal workpiece

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210‧‧‧ surface

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220‧‧‧Oxide layer

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230‧‧‧ basal layer

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230A‧‧‧ permeable layer

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240‧‧‧Nano grain structure

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250‧‧‧ hardened layer

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300‧‧‧Reaction chamber

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310‧‧‧Second chamber

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 A1‧‧‧Deoxidized layer fluid

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A2‧‧‧Modified gas

Fig. 1 is a flow chart showing the "method of modifying the surface of a metal workpiece" of the present invention. Fig. 2 is a schematic view showing an impact device of the "metal workpiece surface modification method" of the present invention. Fig. 3 is a schematic view showing the reaction chamber of the "metal workpiece surface modification method" of the present invention. Figures 4 to 7 are schematic views of the "method of modifying the surface of a metal workpiece" of the present invention.

10‧‧‧A metal workpiece with one oxide layer on one surface

20‧‧‧Remove the oxide layer of the metal workpiece

30‧‧‧ penetrates the nano-grain structure with a modified gas and infiltrates the metal workpiece

Claims (10)

A method for modifying a surface of a metal workpiece, comprising: impinging a metal workpiece having an oxide layer on a surface thereof to form a nano grain structure at an impact portion of the metal workpiece; removing the oxide layer of the metal workpiece, And exposing the nano-grain structure; and penetrating the nano-grain structure with a modified gas and infiltrating the metal workpiece, so that the surface of the metal workpiece forms a hardened layer containing the nano-grain structure. The metal workpiece surface modification method according to claim 1, wherein the metal workpiece further has a base layer connected to the oxide layer, and the nano grain structure formed by the impact portion is from the oxidation The surface of the layer penetrates the substrate layer to change the surface grain structure of the substrate layer where the substrate layer meets the oxide layer. The metal workpiece surface modification method according to claim 2, wherein the impact portion penetrates from the oxide layer into the base layer and has a depth of between 0.1 and 1 μm. The metal workpiece surface modification method according to claim 1, wherein the metal workpiece is impacted by a plurality of fine particles having a particle diameter selected from 0.8 to 4.5 mm. The metal workpiece surface modification method according to claim 4, wherein the fine particles impact the metal workpiece at a speed of between 5 and 15 m/s. The metal workpiece surface modification method according to claim 1, wherein in the step of removing the oxide layer of the metal workpiece, the oxide layer is removed by a deoxidation layer fluid, the deoxidation layer fluid It is selected from hydrogen chloride and nitrogen trifluoride. The metal workpiece surface modification method according to claim 6, wherein the time for removing the oxide layer by the deoxidation layer fluid is 0.5 to 5 hours. The method for modifying a surface of a metal workpiece according to claim 1, wherein the modified gas is selected from the group consisting of a nitrogen-containing gas, a carbon-containing gas, or a mixed gas containing carbon and nitrogen. The metal workpiece surface modification method according to claim 7, wherein the modified gas penetrates the nano grain structure and infiltrates into the metal workpiece for a period of 2 to 36 hours. The metal workpiece surface modification method according to claim 1, wherein the hardened layer has a thickness of between 5 and 30 μm.