JP2921140B2 - Surface hardening method and surface hardening member for substrate made of titanium or titanium alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hardening a surface of titanium or a titanium alloy and a surface hardened member.

[0002]

2. Description of the Related Art In recent years, with respect to an automobile engine, there has been a demand for a reduction in the weight of components of the engine as the engine speed increases. For example, taking a rocker arm as an example, a conventional rocker arm is generally formed from an iron-based alloy in which carburizing treatment has been performed on necessary portions. Alternatively, it has been considered to manufacture a rocker arm using a titanium alloy. this is,
Titanium, because the specific gravity while maintaining the same degree of strength and iron is an intermediate degree of iron and aluminum, because weight reduction of the rocker arm to be Miyaka can be achieved.

[0003] Even when the rocker arm is made of titanium or a titanium alloy, the contact portion with the valve top or the cam needs to have excellent wear resistance.
This part needs to be cured.

[0004]

One of the currently considered methods of curing the titanium surface is nitridation. Nitriding can cure only a small part of the titanium surface (for example, a few μm of the surface). It cannot be used for rocker arms. Also, a method of hardening an alloy having high wear resistance by using an alloy is known, but welding is difficult due to the material properties of titanium, and there is a problem that this method is also difficult to employ.

As disclosed in Japanese Patent Application Laid-Open No. 50-28443, a method is known in which Ti or a Ti alloy is coated with a metal or an alloy and then subjected to a hardening treatment. However, the thickness of the hardened layer obtained by this method is about several tens of μm, and there is a problem that a hardened layer having a sufficient thickness cannot be formed as a hardening method for wear-resistant parts such as rocker arms.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hardened layer having a thickness of 1 mm or more on the surface of a titanium or titanium alloy substrate by a relatively easy treatment. , it is possible to form a layer ceramic particles are dispersed, it is possible to obtain a high wear resistance of titanium or a titanium alloy hardener, ceramic
It is an object of the present invention to provide a surface hardened member made of titanium or a titanium alloy having a hardened thick layer in which the hard particles are dispersed .

[0007]

According to a first aspect of the present invention, to solve the above-mentioned problems, nickel, a nickel alloy or a titanium alloy is formed on a surface of a substrate made of titanium or a titanium alloy, and ceramic particles are formed on the surface of the substrate. Form a dispersed coating layer, then at least the boundary portion between the coating layer and the substrate
At temperatures above the eutectic point in the vacuum atmosphere 900-11
Melting and diffusion by heating to a temperature range of 00 ° C, and alloying at least a part of the coating layer and the surface of the substrate by melt diffusion
Then, the ceramic particles dispersed in the coating layer are combined.
It is to be dispersed in the gold portion .

According to a second aspect of the present invention, in order to solve the above-mentioned problems, TiC, WC, B ₄ C, CB
Select from N, TiN, Si ₃ N ₄ , Sialon, SiC
It employs a nickel or titanium braze in which the selected ceramic particles are dispersed.

According to a third aspect of the present invention, there is provided a coating material of a powder of nickel, a nickel alloy or a titanium alloy, wherein ceramic particles are dispersed, Using a compact in which ceramic particles are dispersed.

According to a fourth aspect of the present invention, there is provided a semiconductor device comprising: a base made of titanium or a titanium alloy; and a melt diffusion layer formed on the base. The layer includes nickel, a nickel alloy or a titanium alloy constituent element, and titanium or a titanium alloy constituent element; TiC, WC, B ₄ C, C-BN, TiN, Si ₃
N _4, sialon, ceramic <br/> click particle selected from among SiC is what is dispersed.

According to another aspect of the present invention, there is provided a base material made of titanium or a titanium alloy, a melt diffusion layer formed on the base material, and a coating layer on the melt diffusion layer. Wherein the coating layer is made of nickel or a nickel alloy or a titanium alloy in which ceramic particles are dispersed, the melt diffusion layer is made of a constituent element of a base material and a constituent element of a coating layer , and Dispersed in the coating layer
Containing the same ceramic particles in a dispersed state
Nde is made of.

According to a sixth aspect of the present invention, there is provided a nickel alloy according to the fourth or fifth aspect, comprising carbon, nitrogen, boron, zirconium, copper, tungsten,
It contains at least one or more elements selected from molybdenum.

According to a seventh aspect of the present invention, there is provided a molten diffusion layer according to the fourth or fifth aspect, wherein a compound of nickel and titanium or a compound of titanium and a constituent element of a nickel alloy are provided. It is a mixture of ceramic particles.

[0014]

According to the present invention, a molten diffusion layer made of nickel or a nickel alloy or a titanium alloy in which ceramic particles are dispersed is formed on the surface of a base material made of titanium or a titanium alloy. The element and the constituent elements of nickel or a nickel alloy undergo a melt-diffusion reaction to cause hardening due to eutectic alloying, further cause precipitation hardening due to the precipitation of the compound, and further strengthen the dispersion by ceramic particles. The diffusion layer cures the substrate surface. In addition, the ceramic particles have good compatibility with nickel alloys and titanium alloys, and if they are uniformly dispersed in the coating layer, they are uniformly dispersed in the melt diffusion layer even after performing melt diffusion. Therefore, segregation of the ceramic particles does not occur. Specific examples of such ceramic particles
And TiC, WC, B ₄ C, C-BN, TiN, Si ₃
Ceramics selected from N ₄ , Sialon and SiC
These ceramic particles can be selected
Can reliably cure the base material surface
You. Further, since the constituent elements of the coating layer are diffused to the base material surface side and the base material constituent elements are also diffused to the coating layer side, the hardness gradient gradually changes at the boundary between the base material and the melt diffusion layer. Become like

Since the melt diffusion layer is excellent in abrasion resistance, the surface hardened member obtained by the present invention is suitable for a machine part requiring abrasion resistance such as a rocker arm. Further, since the base material of the present invention is only titanium or a titanium alloy, the mechanical parts obtained by using the surface-hardened member of the present invention are lighter and have the same strength as conventional iron-based materials. It also has excellent wear resistance.

Further, according to the melt diffusion reaction between the constituent elements of the base material and the constituent elements of the coating layer, the mutual diffusion speed of the diffused atoms can be increased, so that a thick melt diffusion layer can be obtained. When the thick melt diffusion layer is formed on the base material, the base material can be plastically worked, and the base material surface can be cut.

By using a powder coating or a compact as the coating layer, the thickness of the coating layer can be freely controlled, and a cured layer having a desired thickness can be formed.

Hereinafter, the present invention will be described in more detail.

FIG. 1 shows a rocker arm obtained by applying the method of the present invention. The rocker arm 1 of this example includes a bearing portion 2 and arm portions 3 and 4 extending on both sides of the bearing portion 2. A first contact portion 5 that slides on a cam is provided at the tip of the arm portion 3. At the tip of the arm 4, second contact portions 6 slidably contacting the valve shaft are formed.

The rocker arm 1 is made of titanium or a titanium alloy, and its contact portions 5, 6 are subjected to a hardening treatment according to the method of the present invention. Ti-6Al-4V alloy, Ti-13V-11 as the titanium alloy constituting the rocker arm
Cr-3Al alloy, Ti-5Al-2Cr-1-Fe alloy, Ti-5
An Al-3Mn alloy or the like can be exemplified, but other titanium alloys may be used.

As shown in FIG. 2, the cross-sectional structure of the contact portions 5, 6 comprises a base material 7 made of titanium or a titanium alloy and a melt diffusion layer 8 coated on the surface of the base material 7. . The melt diffusion layer 8 has a thickness of 0.7 to 1.0 mm or more, but can be formed thinner if the thickness of a coating layer described later is adjusted.

In order to form the melt diffusion layer 8, first, FIG.
The coating layer 9 is formed on the surface of the substrate 7 shown in FIG. It is preferable to use a metal which forms a compound such as an intermetallic compound, a carbide, a nitride, or a boride with titanium as a metal constituting the coating layer 9.
Specifically, pure nickel, Ni-7Cr-3B-4Si-3Fe
Alloy, Ni-15Cr-3B alloy, Ni-25Cr alloy, Ni-0.
5C-3Si-10Cr-2.5Fe-2B-0.1Co alloy (Colmonoy No4), Ni-0.65C-12Cr-4.25Fe-4.
0Si-2.5B alloy (Colmonoy No5), Ni-1.5C-2
7Cr-8W-1.6Fe-1.55B-0.5Co alloy (Colmonoy No84), 50Ni-32Mo-15Cr-3Si alloy (Trivalloy 700), JIS-specified BNi, etc. Nickel brazing, Ti-48Zr-4Be , Ti-30V-4B
e, Ti-33Cr, Ti-13V-11Cr-3Al and the like can be exemplified, but not limited thereto.

The coating layer 9 is formed by dispersing ceramic particles in the metal having the above composition. TiC, WC, B ₄ C, C-BN, Ti
Examples thereof include N, Si ₃ N ₄ , Sialon, and SiC, but are not limited thereto. Here, for example, whiskers may be mixed as the ceramic particles.

The means for forming the coating layer 9 on the substrate 7 is as follows. A metal foil of each of the above-described compositions in which ceramic particles are dispersed is bonded to the substrate 7 by a method such as pressure bonding, adhesion, spot welding or the like. It may be formed, or a coating material in which a metal powder and a ceramic particle having the above composition are mixed with a binder may be applied. Further, after the metal powder having the above-mentioned composition including the ceramic particles is spread on the base material 7, the metal powder may be densely coated by a technique such as hydraulic pressing. In short, any known means may be used as long as it is a means in which the ceramic particles are uniformly dispersed and a coating layer 9 having a certain thickness can be formed. By the above means, the coating layer 9 having a thickness of about several mm can be easily formed.

After the coating layer 9 is formed, it is housed in a vacuum furnace or the like, and is placed, for example, in a vacuum of 1 × 10 ⁻⁴ Torr or less.
Heat to 0-1100 ° C. The treatment in vacuum is for the purpose of preventing titanium from being chemically active and reducing. The heating temperature is preferably a temperature in the vicinity of the eutectic point of the main constituent element of the coating layer 9 and titanium, and may be a higher temperature. Therefore, the range of 900 to 1100 ° C. is preferable as described above, but the heating temperature is appropriately set within the above range depending on the type of the coating layer 9.

Part or all of the coating layer 9 is melted and diffused by the vacuum heating treatment. By maintaining such a melt diffusion state for a predetermined time (several tens to several tens of hours), the elements constituting the coating layer 9 and the elements constituting the base material 7 mutually diffuse, and after cooling, the melt diffusion shown in FIG. Layer 8 forms. In addition, since the ceramic particles are well adapted to the coating layer 9 during the melt diffusion of the coating layer 9, the ceramic particles are also uniformly dispersed in the melt diffusion layer 8.

The hardness of the melt diffusion layer 8 is Ti-6Al-4.
Ni-1.5C-27Cr-8W-1.6Fe-1.5 in which TiC particles are dispersed is used as a coating layer 9 using a V alloy base material 7.
Using 5B-0.5Co alloy (Colmonoy No84), 107
When heated at 0 ° C. for 1 hour, a Vickers hardness of about 710 is obtained. In the coating layer 9, the Colmonoy No. 84 alloy and the TiC particles were mixed at a volume ratio of 1: 1.
It is blended in.

Here, by performing the melt diffusion treatment, a eutectic alloy of nickel and titanium is formed, and further, an element selected from carbon, silicon, boron, nitrogen, zirconium, and chromium, Binary or 3 with titanium
The eutectic alloying of the base system and the formation of the intermetallic compound occur, and the melt diffusion layer 8 having higher curing than the coating layer 9 is formed. The γ 'phase such as Ni ₃ (Al + Ti) can be exemplified as the intermetallic compound generated by the melt diffusion reaction. When a nickel alloy is used for the coating layer 9, carbon is carbide, silicon is silicide, boron is boride, nitrogen is nitride, and zirconium, niobium and chromium form intermetallic compounds and contribute to hardening. Furthermore, the ceramic particles that are well compatible with the coating layer 9 in the melt diffusion state contribute to the hardening of the melt diffusion layer 8.

When the coating layer 9 is melted by heating,
Using a means such as high-frequency heating, a part of the coating layer 9 on the substrate 7 side may be melted, or the entire coating layer 9 may be melted.

FIG. 5 shows an enlarged structure of the melt diffusion layer 8. The melt diffusion layer 8 includes a base layer 11 and the base layer 1.
1 on the hardened layer 12. That is, the base layer 11 is formed by diffusing the constituent elements of the coating layer 9 toward the base material 7, and the hardened layer is formed by diffusing the constituent elements of the base material 7 into the melt diffusion layer 8. Twelve.

The melt diffusion layer 8 is formed by diffusing the constituent elements of the coating layer 9 into the titanium or titanium alloy base material 7, and the hardened layer 12 is formed by adding the constituent elements of the base layer 7 to the constituent elements of the coating layer 9. Since it is formed by diffusion, if the concentration gradient of the diffusion element is gentle, the boundary between the base layer 11 and the hardened layer 12 may not be clear. Here, the hardened layer 12 is harder than the base layer 11. That is, the hardness distribution is inclined, and the structure is such that the hardness is gradually improved from the base layer 11 on the base material 7 side to the hardened layer 12 side.

The surface hardened member having the structure in which the hardness is smoothly reduced as described above, when used, even if the hardest part of the surface is worn, the wear resistance is gradually reduced, and the wear is rapidly advanced. Therefore, there is no problem that the balance with the surrounding parts is lost. That is, in the case of the rocker arm 1 as an example, a problem does not occur such that the contact area with the valve top is not rapidly abraded, the valve clearance is not too large, and a tapping sound is generated.

On the other hand, in the ordinary hardening method using an overlay, it is usual to carry out alloying between the base material and the overlay as much as possible so that the hardness is not reduced. In addition to promoting the alloying, the hardness can be increased more than the embossed metal, and the change in hardness of the melt diffusion layer 8 can be smoothly reduced to be continuous with the base material 7.

FIG. 6 shows an embodiment in which the hardened material of the present invention is applied to a ring gear 30. In the ring gear 30, the outer gear portion is hardened by the method of the present invention. A general portion of the entire ring gear 30 is made of titanium or a titanium alloy by ordinary means such as forging, and thereafter, a coating layer is formed on the entire outer peripheral gear portion and hardened, and thereafter, cutting or polishing is performed. The ring gear 30 can be obtained by finishing the gear portion.

The melt diffusion layer 8 according to the present invention has a thickness of a few
Since it has a sufficient thickness of several mm, cutting and plastic working become possible. Therefore, it is possible to manufacture a mechanical part that requires cutting or plastic working at the time of manufacturing from titanium or a titanium alloy.

In the above-described example, an example in which the method of the present invention is applied to the rocker arm 1 and the ring gear 30 has been described. However, other members requiring abrasion resistance (a valve retainer, a transmission gear, a differential gear,
Of course, the present invention may be applied to disc brakes, bearings, and the like).

[0037]

Example: Using a substrate made of titanium or a titanium alloy,
A coating layer of various compositions having a thickness of 0.5 mm in which ceramic particles are dispersed is formed on the surface of the base material by a powder coating method,
The base material with the coating layer was housed in a vacuum heating furnace, and the inside of the vacuum heating furnace was evacuated to 1 × 10 ⁻⁴ Torr.
The mixture was heated to 0 to 1100 ° C. for 1 hour to perform a melt diffusion treatment.

The obtained base material having a melt diffusion layer was coated with a ring of Stellite # 1 having a Vickers hardness of 802 and a hardness of HRC.
Abrasion rate by sliding contact with JIS-specified SUJ ring of -57
(m / sec) and the specific wear amount were measured. For this measurement,
Ogoshi abrasion tester was used. This Ogoshi type abrasion tester is a rapid abrasion tester manufactured by Tokyo Testing Machine Co., Ltd., which is worn by pressing a rotating disk against a flat test piece, and the amount of abrasion is measured by the size of abrasion marks at that time. It is a device to do.
Now, the outer diameter of the rotating disk is 2r, the thickness is B, the final load when worn by the wear distance l0 is Po, and the depth of the wear mark is bo.
Then, the wear amount (volume) is represented by Bbo ³ / 12r mm ³ , the contact pressure is represented by Po / Bbo kg / mm ² , and the specific wear amount Ws indicating the wear characteristics of the test material is Bb ³ / 8rPolo mm ² / k
Indicated by g.

The dimensions of the rotating disk were such that a cylindrical member having an outer diameter of 28 mm and a flange having a thickness of 3 mm and an outer diameter of 30 mm were formed on the outer peripheral portion, and the flat test piece had a length of 40 to 60 mm. , Width 25mm, thickness 5-10m
m, the rotating disk is attached to the tip of the rotating shaft, and the flange portion of the rotating disk is pressed against the test piece at a required pressure to drive the rotating shaft to rotate. After rubbing a predetermined distance, the test was stopped to measure wear marks, and the specific wear amount was calculated by calculation.

FIGS. 7 and 8 show the results of forming a coating layer of each composition on a titanium or titanium alloy base material and performing a wear resistance test on their wear resistance.

# 6 shown in FIG. 7 is Co-3Ni-28Cr-4W.
-1C shows stellite # 6 having a composition of # 1C, and # 1 represents Co-3.
Stellite # 1 having a composition of Ni-30Cr-12W-2.5C
And Ti alloy indicates a titanium alloy having a composition of Ti-6Al-4V. From FIG. 7, it can be seen that the sample formed by forming a coating layer of a Col-Monoy alloy containing Ti-C on a titanium alloy substrate and melt-diffusion has a particularly high abrasion resistance when the wear rate is higher than other samples. It turned out to be excellent.

In the sample shown in FIG. 8, Colmonoy N
Both the sample in which the coating layer mixed with o4 and TiC was coated on the titanium alloy base material and the sample in which the coating layer mixed with Colmonoy No84 and WC were excellent in wear resistance as compared with the other samples. Demonstrated the nature. Some of the samples having good abrasion resistance shown in FIG. 8 hardly increase the specific abrasion amount even if the abrasion speed is improved, so that it is apparent that they have excellent high-speed abrasion resistance. is there. Furthermore, Ti-6Al-
An excellent value of 709 in Vickers hardness was obtained in the sample of the coating layer of Colmonoy No. 84 in which TiC was dispersed using a base material of 4V alloy.

FIG. 9 shows the hardening obtained by coating and pressing a foil of Colmonoy No. 4 in which TiC is dispersed on the surface of a Ti or Ti-6Al-4V alloy base material and then performing a melt diffusion treatment at 1100 ° C. for 1 hour. The measurement result of the hardness according to the depth from the surface of the member is shown. From the results shown in FIG. 9, the cured member according to the present invention has the highest hardness of the surface portion,
It became clear that the hardness became lower as the depth became deeper.

In surface hardening member present invention, on a substrate of titanium or a titanium alloy to form nickel, a melt diffusion layer of a nickel alloy or titanium alloy, dispersion strengthened, eutectic alloy of ceramic particles, Because the compound is precipitation hardened, this melt diffusion layer itself hardens,
Cure the substrate. Since ceramic particles familiar a coating layer in a molten state it can be satisfactorily uniform dispersion can be cured to form a uniform hardness. Further, the coating layer can be easily formed to a thickness of several mm, and this thick coating layer is melted to form a melt diffusion layer, so that a melt diffusion layer having a thickness of several mm can be easily obtained. Can be. Surface hardening member obtained by the method of the present invention I O is cutting the composition processing becomes possible, it is possible to provide a mechanical component that is the rocker arm and the valve retainer, the wear resistance of various gears request. Also, as specific ceramic particles,
TiC, WC, B ₄ C, C-BN, TiN, Si ₃ N ₄ ,
Iaron, ceramic particles selected from SiC
These ceramic particles can be melt-expanded.
By uniformly dispersing in the dispersed layer, the surface hardness
It is possible to reliably obtain a chemical material. Since the constituent elements of the melt diffusion layer and the base material are mutually diffused, the base material at the boundary portion is strengthened. As a result, even if the melt diffusion layer is worn, the wear resistance is slowly reduced, and the wear resistance is not suddenly reduced. Therefore, in the sliding portion such as the rocker arm, even if the wear progresses, the valve clearance does not suddenly increase, and the tapping sound does not occur. Further, the surface hardened member of the present invention,
Since the inside is made of titanium or a titanium alloy, it has features that it is lighter, has better corrosion resistance, and has higher strength than conventional iron-based materials.

[Brief description of the drawings]

FIG. 1 is a side view showing an example of a rocker arm obtained by applying a hardening material according to the present invention.

FIG. 2 is a sectional view showing a melt diffusion layer.

FIG. 3 is a sectional view of a base material.

FIG. 4 is a cross-sectional view showing a state where a coating layer is formed on a base material.

FIG. 5 is a cross-sectional view showing another example of the melt diffusion layer.

FIG. 6 is a perspective view of a gear obtained by applying the hardening material according to the present invention.

FIG. 7 is a first graph showing the relationship between the specific wear amount and the wear rate.
It is a graph of.

FIG. 8 is a second graph showing the relationship between the specific wear amount and the wear rate.
It is a graph of.

FIG. 9 is a graph showing the relationship between the hardness and the depth of the cured layer.

[Description of Signs] 1 Rocker arm 3 Arm part 4 Arm part 5 Contact part 6 Contact part 7 Base material 8 Melt diffusion layer 9 Coating layer 11 Base layer 12 Hardened layer

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroo Ozeki 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsui Materials Corporation Product Development Center (72) Inventor Junya Oe 1-297 Kitabukuro-cho, Omiya-shi, Saitama Address Mitsubishi Materials Corporation Product Development Center (56) References JP-A-62-270277 (JP, A) JP-A-2-250951 (JP, A) JP-B-55-48586 (JP, B2) ( 58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 12/00-12/02 C23C 10/28-10/30 C23C 26/00

Claims (7)

(57) [Claims] 1. A coating layer made of nickel, a nickel alloy or a titanium alloy and having ceramic particles dispersed thereon is formed on a surface of a substrate made of titanium or a titanium alloy, and then at least a boundary portion between the coating layer and the substrate. The vacuum atmosphere
At a temperature of 900 to 1100 ° C at a temperature above the eutectic point
Melted and diffused by heating to a temperature range , alloying at least a part of the coating layer and the substrate surface portion by melt diffusion ,
The ceramic particles dispersed in the layer are separated into alloyed parts.
A method for hardening a surface of a substrate made of titanium or a titanium alloy, characterized by being dispersed . 2. A coating layer comprising TiC, WC, B ₄ C,
C-BN, TiN, Si ₃ N ₄ , Sialon, SiC
2. The method for hardening a surface of a substrate according to claim 1, wherein nickel brazing or titanium brazing in which ceramic particles selected from the following are dispersed is used. 3. A coating material of nickel, nickel alloy or titanium alloy powder as a coating layer , wherein TiC, W
C, B ₄ C, C-BN, TiN, Si ₃ N ₄ , Sialon,
A ceramic particle selected from SiC dispersed therein, or a compact of the powder, wherein TiC,
WC, B ₄ C, C-BN, TiN, Si ₃ N ₄ , sialo
2. The method for hardening a surface of a substrate according to claim 1, wherein ceramic particles selected from the group consisting of SiC and SiC are dispersed. 4. A substrate made of titanium or a titanium alloy,
And a melt diffusion layer formed on the substrate,
A surface hardened member, wherein the melt diffusion layer contains nickel, a nickel alloy or a titanium alloy constituent element, and titanium or a titanium alloy constituent element, and is formed by dispersing ceramic particles. 5. A substrate made of titanium or a titanium alloy,
A melt diffusion layer formed on the base material, and a coating layer on the melt diffusion layer, wherein the coating layer is made of nickel or a nickel alloy or a titanium alloy in which ceramic particles are dispersed; The melt diffusion layer is composed of the constituent elements of the base material and the constituent elements of the coating layer , and is dispersed in the coating layer.
Same ceramic particles as the dispersed ceramic particles
A surface hardened member characterized by comprising: 6. The nickel alloy comprises carbon, nitrogen, boron,
The surface-hardened member according to claim 4, wherein the member includes at least one element selected from zirconium, copper, tungsten, and molybdenum. 7. A molten diffusion layer comprising: a compound of nickel and titanium or a compound of titanium and a constituent element of a nickel alloy;
TiC, WC, B ₄ C, C-BN, TiN, Si ₃ N ₄ ,
The surface hardened member according to claim 4 or 5, wherein ceramic particles selected from Iaron and SiC are mixed.