JPH0598438A - Formation of surface modified layer excellent in wear resistance - Google Patents

Abstract

PURPOSE:To provide the method for forming a surface modified layer remarkably improving the wear resistance of a metallic material by thickly forming a surface modified layer by B<+> ion implantation. CONSTITUTION:This method is the method for forming a surface modified layer excellent in wear resistance on the surface of a metallic material by executing ion implantation treatment, and a TiB2 thin film has previously been formed on the surface of the above metallic material by a sputtering method, and after that, B<+> ion implantation is executed, by which B in the TiB2 thin film is diffused and infiltrated over the surface of the metallic material by utilizing the effect of emitting B in the TiB2 thin film to the above metallic material.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a method of forming a surface modification layer on the metal surface, such as steel or Ti by implanting B ⁺ ions, in particular B ⁺ ion implantation with the surface modified layer of conventional The present invention relates to a technique for dramatically improving the wear resistance of the surface modified layer by making the thickness of the ion-implanted layer about three times as thick.

[0002]

2. Description of the Related Art Ion implantation treatment on the surface of a metal material has attracted attention as a material surface modification method capable of forming a surface modification layer by a room temperature process, and various studies have been made particularly for the purpose of improving wear resistance. Is being carried out. However, although many research reports have been made so far, there are very few examples of application to practical products. This is because the modified layer formed by ion implantation does not have the property of competing with other surface modification techniques, and the biggest cause is the shallowness of the modified layer. For example, when B ⁺ ion implantation is performed on a steel substrate at an energy of 40 KeV, the depth of the ion implantation layer is only 0.1 μm or less, and therefore, even if the ion implantation is performed, the abrasion resistance of the surface modification layer is sustained. It is insufficient as a practical material.

[0003]

Ion implantation is a technique for forcibly adding an element to the surface of a metal material, but the amount added is limited. When the composition of the additive element in the metal material reaches saturation after performing the ion implantation process for a long time, the implantation B diffuses into the substrate and the thickness of the implantation layer reaches about 0.6 μm. However, even if the implantation is continued further, excess ions that cannot be contained in the metal material will return to the surface of the metal material, forming a deposited layer of only the implanted ion elements on the surface, resulting in ion implantation formed in the metal material. The layer thickness does not exceed about 0.6 μm. Also, the B thin film deposited on the surface has poor adhesion, and improvement of wear resistance by this film can hardly be expected.

The present invention has been made in view of the above circumstances, and by forming a thick surface modification layer by B ⁺ ion implantation, surface modification which dramatically improves the wear resistance of a metal material. It is intended to provide a method for forming a layer.

[0005]

Means for Solving the Problems The present invention, which has achieved the above object, is a method for forming a surface-modified layer having excellent wear resistance on a surface of a metal material by performing an ion implantation treatment. A TiB ₂ thin film is previously formed on the surface of the material by a sputtering method, and then B ⁺ ion implantation is performed to utilize the B release effect of the TiB ₂ thin film on the metal material to remove the B in the TiB ₂ thin film. It has a gist in that it is diffused and permeated into the surface of the metal material.

[0006]

Function As described above, B is applied to the surface of a metal material such as steel or Ti.
^{When +} ion implantation is performed, the B composition inside the metal material is saturated, and excess implanted B ⁺ ions flow back to the surface of the metal material and are deposited outside the metal material. Therefore, the thickness of the ion-implanted layer on the surface of the metal material cannot be 0.6 μm or more.

On the other hand, in the present invention, a TiB ₂ thin film is previously formed on the surface of the metal material by the sputtering method, and then B ⁺ ion implantation is performed. This TiB
_{The 2} thin film can temporarily store the B ⁺ ions that have been ion-implanted thereafter, but the TiB ₂ thin film releases B when different metals or the like come into contact with each other at high temperature.
And has the property of borating the contact metal. Due to these properties, the TiB ₂ thin film acts as a diffusion source of B in the metallic material. Under such circumstances B
^{When +} ion implantation is continuously performed, B ⁺ ions are implanted into the TiB thin film after B is released into the metal material and T ⁺ is again implanted.
An iB ₂ thin film is formed, and this TiB ₂ thin film starts to release B into the metal material again. By repeating such a process, B efficiently diffuses and penetrates into the metal material. Thus, according to the method of the present invention, the thickness of the ion-implanted layer is 2 to 3 μ, which is three times or more the normal thickness.
It can be formed up to about m. Also, due to the difference in diffusion coefficient between the TiB ₂ film and the metal material, the implantation B supplied inside the metal material
^{The +} ion atoms are blocked by the TiB ₂ thin film and cannot return. TiB ₂ formed on the surface of the metal material
It is suitable that the thickness of the thin film is about 200 to 500 nm, and if the film is too thin or too thick, B will not be released to the metal material.

The present invention will be described in more detail with reference to the following examples. The following examples are not intended to limit the scope of the present invention, and any change in the design of the present invention can be made in view of the purpose of the former or later stages. It is included in the technical scope.

[0009]

[Examples] Mirror-polished carbon steel (SS400) was used as a substrate, and surface treatment was performed under the following two conditions. (1) Surface treatment 1 [prior art] B ⁺ ion implantation treatment Energy: 40 KeV Ion beam current density: 0.8 A / m ² Implantation amount: 5 × 10 ²² ions / m ² (2) Surface treatment 2 [technology of the present invention] After a TiB ₂ thin film is formed on the substrate surface by Ar sputtering using a TiB ₂ target, B ⁺ ion implantation treatment is performed. B ⁺ ion implantation conditions are the same as in the above surface treatment 1. TiB ₂ thin film thickness: 200 nm

AES analysis was performed on the test pieces subjected to the above two surface treatments to examine the composition distribution in the depth direction, and the hardness of the surface of the modified layer was measured by a micro Vickers hardness meter under a load of 10 kgf. Figure 2 shows surface treatment 1
It is an AES profile of the test piece which gave. The B atom injection layer is formed only up to a thickness of about 0.6 μm in the substrate of the test piece. Due to this modified layer, the surface hardness of the test piece slightly increased from 120 Hv to 190 Hv. However, since the single-layer B layer has poor adhesion and poor bonding state, it does not have sufficient properties as a wear-resistant modified layer.

FIG. 1 is an AES profile of a test piece subjected to the surface treatment 2 according to the present invention. Unlike the case of the surface treatment 1, the B atoms penetrate deeply into the substrate, which indicates that the TiB ₂ thin film previously formed on the substrate surface has released the B atoms into the substrate. With this modified layer, the surface hardness of the test piece was remarkably improved from 120 Hv to 1300 Hv, and sufficient properties could be obtained as a wear resistant modified layer.
It is considered that this is because the Fe ₂ B layer having a hardness as high as 1500 Hv was formed in the substrate.

Next, with respect to the above-mentioned two surface-treated test pieces, a change in friction coefficient was investigated when the specimen was reciprocally slid with an alumina ball indenter at a load of 300 gf. The result is shown in FIG. For comparison, FIG. 3 also shows the results when a reciprocal sliding test was conducted using the substrate. The number of reciprocating slides was 25 for the test piece that had been subjected to surface treatment 1.
It can be seen that the friction coefficient exceeds 0.30 due to wear after about one turn. On the other hand, in the test piece subjected to the surface treatment 2, the coefficient of friction was around 0.25 even after reciprocating 90 times or more, and the wear resistance life of the steel (substrate) was improved 20 times or more.

[0013]

EFFECTS OF THE INVENTION The present invention is constituted as described above, and a surface-modified layer capable of dramatically improving the wear resistance of a metal material can be formed.

[Brief description of drawings]

FIG. 1 AES of a test piece subjected to a surface treatment according to the present invention
It is a graph which shows a profile.

FIG. 2 is a graph showing an AES profile of a test piece that has been subjected to a conventional surface treatment.

FIG. 3 is a graph showing the relationship between the number of times of reciprocal sliding and the coefficient of friction in a reciprocal sliding test.

Claims (1)

[Claims] 1. A method for forming a surface-modified layer having excellent wear resistance on a surface of a metal material by performing an ion implantation process, wherein TiB is formed on the surface of the metal material by a sputtering method.
Formed in advance ₂ thin film, by the subsequent B ⁺ ion implantation performed a child stranded, diffuse infiltrate B of the TiB ₂ thin film by utilizing a B release effect of the metal material in the TiB ₂ thin film to the metal surface A method for forming a surface-modified layer having excellent wear resistance, which is characterized by the above.