KR20150012377A - Durability test method of hard coatings by using pulsed laser - Google Patents
Durability test method of hard coatings by using pulsed laser Download PDFInfo
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- KR20150012377A KR20150012377A KR1020130087787A KR20130087787A KR20150012377A KR 20150012377 A KR20150012377 A KR 20150012377A KR 1020130087787 A KR1020130087787 A KR 1020130087787A KR 20130087787 A KR20130087787 A KR 20130087787A KR 20150012377 A KR20150012377 A KR 20150012377A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
- G01N17/004—Investigating resistance of materials to the weather, to corrosion, or to light to light
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/30—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0001—Type of application of the stress
- G01N2203/0005—Repeated or cyclic
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/006—Crack, flaws, fracture or rupture
- G01N2203/0062—Crack or flaws
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0091—Peeling or tearing
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Abstract
The present invention relates to an apparatus for testing durability under a temperature-stress composite stress of a hard coating, and is a test method for simulating a practical use condition of a cutting tool to which a hard hard coating is applied by a pulsed laser. High hardness coating causes high temperature due to friction at the contact area with the base material depending on the use conditions, and it quickly cools down after work and breakdown occurs in the local part. Accordingly, the present invention provides a method for evaluating the durability of a high hardness coating using a pulsed laser capable of applying thermal and mechanical impact with high energy and momentarily applying stress to a local site.
Description
The present invention relates to a durability evaluation and testing method of a high hardness coating material using a pulsed laser, and more particularly, to a hardness coating material used for a cutting tool, in which thermal and mechanical shocks To a test method using a pulsed laser.
In case of cutting tool with high hardness coating, the temperature rises up to 1000 at the contact area with the workpiece depending on operating conditions and it is cooled quickly after work. Repeated mechanical and thermal shocks can cause delamination, cracking, and spalling at the interface between the base material and the coating layer of the hardened material.
The durability evaluation method of the high hardness coating by the heat-shock repetition method using the conventional chamber is difficult to apply the rapid temperature change similar to the actual use condition and the whole specimen is exposed to the heat and the repetitive stress is applied to the local part There is a limit to apply.
The thermal shock method of high hardness coating material using pulsed laser can instantaneously apply stress to a local part of the coating and can cause rapid temperature change. In addition, since heat and mechanical stress can be applied at the same time, it is possible to evaluate the durability in an environment similar to actual use conditions as compared with a conventional chamber.
In addition, testing of high-hardness coating materials can be done by adjusting the laser output power, and testing can be performed in a short time because repetitive stress can be applied to a local part.
Although the durability evaluation method of the high hardness coating material using the chamber is not related to the actual use environment in the durability evaluation due to the influence of the oxidation due to the oxidation, the durability evaluation method using the pulse laser is similar to the actual use environment of the hardness coating material Durability evaluation in the environment is possible.
It is an object of the present invention to provide a test method for evaluating durability in a condition similar to a use environment of a cutting tool in which a high hardness coating is used by using pulse laser equipment.
According to an aspect of the present invention, there is provided a method of evaluating the durability of a high hardness coating material for a cutting tool.
The method for evaluating the durability of the high hardness coating material for a cutting tool includes preparing a test specimen, irradiating the specimen with a laser, and observing the microstructure and hardness of the specimen under test.
According to one embodiment of the present invention, the base material of the hard coating sample can be variously manufactured according to the use environment such as Si, SUS304, and multi-component cemented carbide, and the coating material can also be variously manufactured such as TiN, TiAlN, TiCN, cBN have.
According to an embodiment of the present invention, the laser apparatus should be capable of controlling the output and the number of times of irradiation.
According to one embodiment of the present invention, the laser irradiation test is a method of repetitively irradiating a high-hardness test piece to a local portion with a preset output through a preliminary experiment.
According to one embodiment of the present invention, the durability evaluation method of the hard coating material through the laser irradiation test may be a relative comparison of the microstructure and the hardness according to the output and the number of times of irradiation.
The durability evaluation method for the hard coating material for cutting tool according to the embodiment of the present invention can confirm the deterioration behavior and durability of the coating material under conditions similar to actual use environment by using pulse laser equipment. In addition, since the test method is relatively simple, the test time can be shortened and it is economical.
In addition, the durability evaluation method for a high hardness coating material for a cutting tool according to an embodiment of the present invention can be used as a basic data for accelerated life test by correlating the applied stress with the use environment condition through controlling the laser output and the number of irradiation .
Referring to FIG. 1, a specimen is prepared in step C10. Here, the base material of the specimen may be composed of Si, SUS304, multi-component cemented carbide, etc., and the coating material may also be made of TiN, TiAlN, or the like. In addition, the shape of the specimen can be varied but must be made to be fixed to the pulsed laser equipment.
The present invention can be applied to various types of specimens and various modifications can be made. The characteristic embodiments are illustrated in the drawings and will be described in detail with reference to the drawings. However, it should be understood that the present invention is not limited to the specific embodiments but is included in the technical scope of the present invention.
Hereinafter, a method for evaluating durability of a high hardness coating material using a pulse laser according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring to FIG. 1, a specimen is prepared in step C10. Here, the base material of the specimen may be composed of Si, SUS304, multi-component cemented carbide, etc., and the coating material may also be made of TiN, TiAlN, or the like. In addition, the shape of the specimen can be varied but must be made to be fixed to the pulsed laser equipment.
In step C20, a thermal shock test is performed on the hard-coated material using a pulsed laser apparatus. Hereinafter, (C20) will be described with further reference to FIG. 2 and FIG.
FIG. 2 is a view of a pulse laser as an apparatus to be performed in a durability evaluation and test method of a high hardness coating material according to an embodiment of the present invention. 3 is a view illustrating a pulse laser thermal shock test according to an exemplary embodiment of the present invention.
Referring to Figures 2 and 3, a specimen is installed in a pulse laser apparatus. The pulse laser device includes a program for adjusting the irradiation conditions such as the output value and the output interval, and a chiller for continuous cooling.
Such a pulsed laser tester applies a laser to the localized area of the specimen to perform a thermal shock test similar to the environment in which the cutting tool is used. Here, the test conditions are set as the output of the laser and the number of repetitions, and the change in the microstructure of the surface, the decrease in hardness and the deterioration of the interface due to the thermal shock test are reflected in the durability evaluation of the specimen.
Perform basic tests to find appropriate conditions by varying the laser power according to the shape and thickness of various high hardness coating materials. At this time, the output of the specimen is varied, and the microstructure is observed through a microscope after one irradiation, and the output of the laser generating a fine crack on the surface is selected as the optimum condition. When selecting the laser equipment, it is difficult to obtain effective lifetime data if the failure occurs at less than 5 times under the minimum output value of the equipment. Therefore, it is possible to obtain appropriate life data under the minimum output value through the durability evaluation test, Should be used.
If the appropriate laser output condition is selected for the specimen, the number of irradiation is gradually increased by controlling the laser Hz, etc., and the laser is repeatedly irradiated to the same portion. At this time, the laser irradiation spot should be the same and it is checked whether the irradiation is repeated at the same point by using the camera of the pulse laser device.
Check the deterioration process by observing the microstructure of the specimen by the number of laser irradiation and confirm the number of times of irradiation until the coating layer is peeled off or melted and removed from the base material.
For specimens with a high hardness coating thickness or a very high hardness,
When the deterioration progresses in such a manner that no peeling of the coating layer occurs even with the laser irradiation, the durability evaluation may be carried out by measuring the change in the surface hardness of the irradiated area according to the number of times of laser irradiation.
The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.
In the first embodiment, a plurality of specimens are divided into a first group and a second group. In the first group, a TiN hard coat is deposited on a SUS304 substrate to a thickness of about 1.0 μm to prepare a specimen for pulse laser durability test. The second group prepared a TiN hardness coating on the Si substrate under the same conditions as in the first group and carried out the durability test in the same way.
Here, the pulsed laser irradiation test is carried out by observing the microstructure while increasing the number of times of irradiation by 50% (about 2.3 J) and spot size of 10 μm.
As can be seen from FIG. 4, after the pulsed laser irradiation under the same conditions, the first group of specimens cracked, pored and melted on the coating surface, but the second group of specimens showed only crack and pore on the coated surface, Was not found. Also, it was confirmed that the surface roughness and thickness of the coating layer of the second group specimen were small, while the surface roughness of the first group coating layer was increased and the thickness of the coating layer was decreased. That is, the durability of the coating layer of the second group specimen was better than that of the first group specimen under the same conditions, and from the graph of hardness change of FIG. 4, it is confirmed that the resistance of the second group specimen to laser heat shock is excellent.
In the second embodiment, a plurality of specimens are divided into a first group and a second group. The first group prepared a specimen of TiN hardness coating deposited on Inconel 617 substrate to a thickness of about 1 μm and conducted the durability test of pulse laser. The second group prepared a TiN hardness coating on Inconel 617 substrate with a TiN hardness coating of about 5 μm thickness and performed the durability test in the same way.
Here, the pulse laser irradiation test is carried out by observing the microstructure while increasing the number of times of irradiation by 100% (about 4.6J) and spot size of 200 μm.
As can be seen from FIG. 5, the first group of specimens was severely cracked by laser irradiation 11 times, and the coating layer was partially peeled off. On the other hand, surface cracks and deterioration are observed in the second group, but no peeling phenomenon is observed. Comparing the specimens irradiated with pulse laser 11 times under the same conditions, the second group seems to be relatively durable against thermal shock of pulse laser.
The durability evaluation and testing method of the high hardness coating using the pulse laser according to the embodiment of the present invention can easily evaluate the durability of the high hardness coating used for the cutting tool by applying the stress similar to the actual working environment .
The deterioration behavior and failure mode of each specimen can be confirmed by checking the microstructure of the surface, coating layer, and interface of the specimen after laser irradiation for various specimens. have.
The foregoing description is merely illustrative of the present invention and various changes and modifications may be made without departing from the essential characteristics of the present invention. Accordingly, it is intended that the embodiments disclosed herein are not intended to limit the scope of the invention, but the scope of protection of the invention should be construed in light of the following claims. And all technical ideas within the scope of equivalents thereof should be interpreted to be included in the scope of the present invention.
100: Automatic control system 200: Pulsed laser source
300: camera 400: test piece
500: before laser irradiation sample 501: after laser irradiation sample
502: Laser irradiation central region
Claims (5)
(a) preparing an evaluation specimen;
(b) performing a durability test on the specimen using a pulsed laser;
(c) evaluating the durability of the hardcoat material after irradiating the pulsed laser.
The above-mentioned specimen base material is made of various shapes and materials according to actual use purpose, and the hardness coating material may also be diversified. In addition, the coating method can be selected in an optimum manner depending on the coating material.
In (b), a laser device is used to apply a temperature-stress composite stress to the hard coating material. In this case, the laser unit is the moment and repeating the pulse-operation research method compared to the continuous behavior of glass and the particular maximum output is high (the number of KW ~ 2 GW / cm 2 range) is advantageous Nd-YAG pulse laser repeated irradiation Recommended.
In case of measuring the hardness value in the laser irradiation area, the minimum laser irradiation area is designated as diameter 200 μm or more so that hardness measurement of 5 times or more can be performed in different areas. In addition, it is possible to interoperate with a computer program, so that irradiation conditions such as irradiation area size, output value, irradiation interval, and the like can be easily controlled.
The above (c) shows a durability evaluation method after laser irradiation based on the output of the pulse laser and the number of times of irradiation in the hard coat material.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20180068414A (en) * | 2016-12-14 | 2018-06-22 | 부산대학교 산학협력단 | Method for measuring a deterioration degree of high hardness coating product by external stress and apparatus for measuring a deterioration degree of high hardness coating product by external stress |
| RU2716496C1 (en) * | 2019-02-08 | 2020-03-12 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Удмуртский государственный университет" | Method of assessing material wear resistance |
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2013
- 2013-07-25 KR KR1020130087787A patent/KR20150012377A/en not_active Application Discontinuation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20180068414A (en) * | 2016-12-14 | 2018-06-22 | 부산대학교 산학협력단 | Method for measuring a deterioration degree of high hardness coating product by external stress and apparatus for measuring a deterioration degree of high hardness coating product by external stress |
| RU2716496C1 (en) * | 2019-02-08 | 2020-03-12 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Удмуртский государственный университет" | Method of assessing material wear resistance |
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