JP2007023317A - Wear resistant titanium material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wear resistant titanium material subjected to Ni-P plating which has high reliability and ensures characteristics such as fatigue life, wear resistance or adherability. <P>SOLUTION: The titanium material is provided with a Ni-P plated film. The Ni-P plated film is a crystalline plated film which is formed from a Ni-alloy containing, by mass, ≥85% Ni, 1-5% P and 0.1-1% NH<SB>4</SB>group and has an average crystallite size of 1-5 nm, in the Ni-P plated film texture analysis by an X-ray diffraction method. At least one layer of a Ni or Ni-alloy layer containing ≥99% Ni and a Pd or Pd-alloy layer containing ≥90% Pd is formed at the interface between the titanium material and the Ni-P plated film. The Ni-P plated film has a hardness of ≥500 Hv in as-plated state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wear-resistant titanium material having a hard plating film on the surface.

  In recent years, in order to promote global environmental conservation, such as reducing carbon dioxide emissions, or to improve the performance and energy saving of machines themselves, transport aircraft such as automobiles and motorcycles, and robots, such as automobiles and motorcycles, or robots In industrial machines such as these, it is required to reduce the weight of components. As part of this lightening measure, the components used for the component parts are being converted from steel materials to pure titanium materials or titanium alloy materials (hereinafter simply referred to as titanium materials). In particular, among the components, if the power transmission component is made of titanium, not only the weight of the power transmission component itself but also the size of the drive device for the power transmission component can be reduced. Great effect.

  In order to improve the wear resistance of the titanium material, in particular, a hard film has been conventionally provided on the surface.

  As the hard film on this surface, Ni-P electroless plating film, which is comprehensively superior in wear resistance, durability and toughness compared to hard surface films such as Cr plating, nitriding and carburizing, is used. It has been.

  For example, Patent Document 1 discloses rolling in which a Ni-P plating layer having a hardness of HV500 or more is directly coated on a surface of a titanium alloy or aluminum alloy whose surface is roughened to Ra 0.5 μm or more and PPI50 is 130 or more. A mechanical structural composite material having an excellent fatigue life is disclosed.

  In Patent Document 2, the surface of titanium or a titanium alloy and aluminum or aluminum alloy whose surface is roughened to Ra 0.5 μm or more and PPI50 is 130 or more, the P content is 4 wt% or more, and the crystal plane orientation < 111> main layer and a composite material for mechanical structure with excellent rolling fatigue life, coated with at least two Ni-P plating layers of P content less than 4% by weight and outer layer with plating hardness of HV500 or more Is disclosed.

  Patent Document 3 discloses that a surface of a titanium alloy or aluminum alloy whose surface is roughened to Ra 0.5 μm or more and PPI50 130 or more is directly coated with a Ni—P plating layer of 100 μm or more, and then room temperature to 200 ° C. or 450 A method for producing a composite material for machine structure excellent in rolling fatigue life after heat treatment at ˜600 ° C. is disclosed.

  In Patent Document 4, in power transmission parts made of a metal base material such as a Ti alloy provided with a hard Ni-P plating film, the plating film is broken due to external stress or impact, or the plating film is used over a long period of time. A technique for preventing fatigue fracture and peeling of itself is disclosed. More specifically, after a hard electric Ni-P plating film is provided on the surface of the metal substrate, heat treatment is performed to increase the hardness and adhesion of the plating film. A technology to improve the hardness and toughness of the plating film in a well-balanced manner by applying residual peening stress to the plating film by recovering shot peening and dry honing, and recovering the decrease in toughness of the Ni-P plating film due to the heat treatment. It is disclosed.

These Ni-P plating film technologies can improve wear resistance, adhesion, and rolling fatigue life. However, mechanical parts used for power transmission and the like tend to have a larger contact stress and a higher operating speed, and the current technology has become insufficient in performance. That is, a surface treatment having excellent adhesion and wear resistance is required.
Patent No. 2777460 (Claims) Patent No. 2777468 (Claims) Patent No. 28888953 (Claims) JP-A-8-39432 (Claims)

  The present invention has been made to solve such problems, and its purpose is to apply highly reliable Ni-P plating that can guarantee characteristics such as fatigue life, wear resistance, and adhesion. Another object of the present invention is to provide a wear-resistant titanium material.

In order to achieve this object, the gist of the wear-resistant titanium material of the present invention is a titanium material provided with a Ni-P plating film, and the Ni-P plating film is in mass%, and Ni: 85% or more. , P: 1 to 5%, NH ₄ group: 0.1 to 1%, and the average crystallite size of the film in the Ni-P plating film structure analysis by X-ray diffraction method is 1 to 5 nm. Whether the Ni or Ni alloy layer is made of 99% or more of Ni or the Pd or Pd alloy layer of Pd is made 90% or more at the interface between the titanium material and the Ni-P plating film. Or at least one of them is formed, and the hardness of the Ni-P plating film as plated is 500 Hv or more.

In the present invention, as described above, the average crystallite size of the Ni—P plating film is reduced in order to ensure characteristics such as wear resistance and adhesion. For this purpose, it is assumed that the Ni—P plating film contains NH ₄ groups.

  As a result, the hardness of the Ni-P plating film as plated increases to 500 Hv or more, and the toughness is increased, making it difficult to crack. Moreover, the lubricity of the Ni—P plating film is also improved.

In the present invention, the degree of orientation of the Ni-P plating film is determined by measuring the peak intensity ratio of Ni (111) and Ni (200) in the film structure analysis by X-ray diffraction method Ni (111) / Ni (200). It is preferable to reduce by setting 0.3 to 0.5. By reducing the degree of orientation of the Ni—P plating film as described above, the toughness is increased to 50 kN or more, while the plating tensile stress is 5 kgf / mm ² or less, and it is difficult to crack even with the high hardness.

  In order to express these effects with good adhesion, Ni or a Ni alloy layer with Ni of 99% or more, or Pd with Pd of 90% or more at the interface between the titanium material and the Ni-P plating film. Alternatively, a Pd alloy layer is formed.

  In order to further improve the wear resistance, a hard Cr plating having an average film thickness of 0.1 to 5 μm and a hardness of 900 Hv or more is applied as an upper layer of the Ni-P plating film. preferable.

  And in order to obtain these plating films reliably, it is preferable that the said Ni-P plating film is electroless plating. Electroless plating is more excellent in film thickness (film thickness distribution) uniformity than electroplating.

  The present invention having the above effects can provide a titanium material and a titanium material part that can ensure high wear resistance.

(Ni-P plating film composition)
First, the Ni-P plating film composition in the present invention will be described. In the present invention, the Ni—P plating film is basically a plating film made of a Ni alloy containing, by mass%, Ni: 85% or more, P: 1 to 5%, NH ₄ group: 0.1 to 1%. The composition.

  Ni and P basically ensure the wear resistance and fatigue life characteristics of the hard coating. For this purpose, Ni is contained at 85% or more, and P is contained at 1% or more. When the content of Ni and P is less than the lower limit, the basic characteristics are deteriorated.

On the other hand, if Ni is contained in excess of 98.9%, the content of other P and NH ₄ groups is insufficient, and the basic characteristics are deteriorated. Therefore, Ni is 85% or more, preferably 98.9% or less.

  Moreover, when P is contained exceeding 5%, the hardness as plated is insufficient. For this reason, the heat processing for making hardness into 500 Hv or more is needed further. Furthermore, the toughness of the plating film is also reduced, and it becomes easy to break. Therefore, P is in the range of 1 to 5%.

The NH ₄ group is contained in the plating film at the time of forming the plating film from the Ni-P plating bath, and the crystal grain size of the plating film is 5 nm or less in terms of the average crystallite size by the X-ray diffraction measurement method. It is presumed to be miniaturized. This ensures basic properties such as wear resistance, fatigue life and plating adhesion in the coating.

In order to exert these effects, the NH ₄ group is contained by 0.1% or more by adjusting the plating bath components. If the NH ₄ group content is less than 0.1%, these effects cannot be exhibited, and the average crystallite size cannot be refined. In addition, the plating bath composition containing no NH ₄ group also enhances the orientation of the plating film, and the degree of orientation of the Ni—P plating film can be determined using Ni (111) and Ni ( 200) and the measurement peak intensity ratio Ni (111) / Ni (200) cannot be made 0.3 to 0.5. On the other hand, even if the NH ₄ group content exceeds 1%, this effect is saturated, and the basic characteristics are lowered. Therefore, the NH ₄ group is contained in the range of 0.1 to 1%.

In addition, the plating film of the present invention allows the inclusion of Co and S. Co contains 0.05% or more and S contains 0.01% or more, and has an effect of improving hardness. However, if the amount is too large, the above-mentioned basic characteristics of the plating film may be deteriorated. Therefore, for Co, the content of Ni, P, NH ₄ groups, etc. can be guaranteed to 1% or less, and for S, the viewpoint of reduced toughness To 3% or less.

In addition, metal elements such as C, B, W, and Mo also have an effect of improving the hardness, and allow the inclusion up to an amount that can guarantee the content of Ni, P, NH ₄ groups, and the like. On the other hand, since Fe, Cu, and Zn may deteriorate the basic characteristics of the plating film, inclusion in a range that does not inhibit the characteristics is allowed.

(Ni-P plating film structure)
In the present invention, characteristically, in the film structure analysis of the Ni-P plating film by the X-ray diffraction method, the average crystallite size of the film is refined to 1 to 5 nm. Further, preferably, in the film structure analysis by the X-ray diffraction method, the measurement peak intensity ratio Ni (111) / Ni (200) of Ni (111) and Ni (200) is 0.3 to 0.5. The plating film is weak or no.

  By refining the average crystallite size of the film, basic properties such as wear resistance and plating adhesion in the hard film are guaranteed.

  On the other hand, for example, in Patent Document 3 described above, in order to improve the Ni—P plating adhesion, the crystal surface orientation of the material to be plated and the crystal plane orientation of the plating are maintained as much as possible. The orientation is positively oriented so that the integral intensity of the plane orientation <111> is 90% or less in the following equation. [<111> / (<111> + <200> + <220> + <311> + <222>)] × 100 ≦ 90.

  However, when the crystal plane orientation of the plating is oriented as described above, the basic characteristics are likely to deteriorate. In addition, the adhesion between the plating film and the titanium substrate can be further improved by the interface layer (intermediate layer) of the present invention without intentionally orienting the crystal plane orientation of the plating.

In the present invention, preferably, the crystal orientation of the plating film is defined by the ratio of peak intensity measured by X-ray diffraction (XRD) between Ni (111) and Ni (200) which are the main crystal plane orientations of the plating film. In addition, the measurement peak intensity ratio is in the range of 0.3 to 0.5. Thus, by weakening the crystal orientation of the plating film, the toughness is increased to 50 kN or more, while the plating tensile stress is 5 kgf / mm ² or less, and it is difficult to crack even with the high hardness.

  When the measured peak intensity ratio is less than 0.3, the orientation of the crystal plane orientation of Ni (200) becomes strong. On the other hand, when it exceeds 0.5, as in the above-described conventional technique, Ni (111) There is a possibility that the orientation of the crystal plane orientation becomes strong and the toughness is lowered, or the plating tensile stress is increased and the basic characteristics are lowered.

(Ni-P plating film thickness)
The average film thickness of the Ni—P plating film having the above composition is preferably selected from the range of 1 to 100 μm. If the average film thickness of the Ni—P plating film is less than 1 μm, the wear resistance may not be guaranteed. On the other hand, when the average film thickness of the Ni—P plating film exceeds 100 μm, the basic characteristics of the plating film including adhesion may be deteriorated.

  According to the present invention, although the average film thickness of the Ni-P plating film is selected from the above range, the distribution (variation) of the average film thickness selected (produced) on the component surface is the maximum film thickness and the minimum film thickness. It is preferable that the difference from the film thickness is small.

(Interface between titanium material and Ni-P plating film)
In order to further improve these effects of the Ni-P plating film, an interface layer (an intermediate layer, an underlayer of the Ni-P plating film) is provided below at the interface between the titanium material and the Ni-P plating film. Each intermediate layer is formed.
(1) Ni or Ni alloy layer comprising Ni of 99% or more.
(2) A Pd or Pd alloy layer comprising Pd of 90% or more.
If the purity of Ni or Pd in each of these intermediate layers is further lowered, there is a possibility that the effects of these intermediate layers cannot be achieved.

(Ni or Ni alloy layer)
On the Ni or Ni alloy layer, Ni plating is likely to be deposited, and it is easy to form a film with good adhesion. However, it is difficult to control the crystallite size and orientation degree of the Ni plating to be deposited, and the crystallite size is large and the orientation degree tends to be strong. If the above-described Ni-P plating bath is used, it is possible to suppress the crystallite size and the degree of orientation within the scope of claims. Desirably, the surface of the Ni or Ni alloy layer is roughened if Ni This is good because a large number of nuclei from which -P plating precipitates can be formed and the crystallite size can be reduced.

(Pd or Pd alloy layer)
The Pd or Pd alloy layer has the effect of refining the crystallite size of the Ni—P plating film because Ni—P plating is precipitated with Pd as a nucleus when Pd is dispersed and precipitated. Moreover, since Ni-P plating is easy to form a film with good adhesion on the Pd surface, the adhesion between the Ni-P plating film and the titanium material is improved.

(Hard Cr plating)
In the present invention, according to the demand for higher hardness from the application, if necessary, as an upper layer of the Ni-P plating film, a hard material having an average film thickness of 0.1 to 5 μm and a hardness of 900 Hv or more. Cr plating may be applied. Hard Cr plating plays a role of mitigating initial strike (impact) when contacting other members. However, especially at high loads, chipping (abrasion due to cracking) is likely to occur, and the lubricity of the Ni-P plating film is reduced. For this reason, when hard Cr plating is provided, the thickness of the film is adjusted so that the hard Cr plating film disappears due to the initial wear, and after the familiarity of the member comes out, it is used without the hard Cr plating film. It is preferable to do.

The Ni-P plating film formed as described above has the basic properties of hardness of 500 Hv or more, more preferably toughness of 50 kN or more and plating tensile stress of 5 kgf / mm ² or less. When the hardness is less than 500 Hv, the wear resistance is insufficient. If the toughness is less than 50 kN, durability such as fatigue life may be insufficient. When the plating tensile stress is less than 5 kgf / mm ² , the residual stress is too high, the adhesiveness is lowered and the crack is easily broken, and the durability may be insufficient.

  In addition, the intermediate layer and the upper layer formed as described above: a film made of a Ni-P plating film, particularly an electroless plating film, in a state where the difference between the maximum film thickness and the minimum film thickness is the best, for example, Uniformity within a range of 0.5 μm, uniform film thickness distribution, and uniform plating film. As a result, there is also an advantage that wear resistance can be guaranteed at any part of the part.

(Film formation method)
The method for forming the coating of the present invention described above will be specifically described below.
In the method of forming the coating of the present invention, if necessary, the surface-roughened titanium substrate is first degreased with a commercially available alkaline degreasing agent and pickled (for example, about 3: 1 nitrofluoric acid at room temperature for about 10 minutes) Washing or washing with hydrochloric acid with a concentration of about 10 g / l for about 10 minutes at normal temperature), activation treatment (washing with sulfuric acid with a concentration of about 10 g / l for about 2 minutes at normal temperature), water washing, etc. Processing is performed as necessary. In addition, in the film formation method of this invention, it includes adding suitably intermediate | middle processes, such as washing, or pre-processing as needed between each plating process demonstrated below.

(Middle layer)
After the pretreatment, first, the above-described intermediate layers are provided.

(Ni or Ni alloy layer forming method)
In a plating bath containing 400 g / l nickel sulfate + 50 g / l nickel chloride + 50 g / l sulfuric acid, energization is performed at a bath temperature of about 50 ° C. and about 5 A / dm ² to perform electroplating for a predetermined time. The Ni concentration (purity) and film thickness of the Ni or Ni alloy layer are controlled by adjusting the number of electroplating treatments, the metal ion concentration, the energization time, and the energization amount.

(Ni or Ni alloy layer roughening method)
The surface of the Ni or Ni alloy layer may be roughened by mechanically or chemically roughening the substrate. However, after the Ni or Ni alloy layer is formed, the surface is mechanically and chemically roughened. May be used. Since it is easy, it is recommended to roughen the surface by forming a Ni or Ni alloy layer and then spraying # 100 glass beads or alumina beads.

(Pd or Pd alloy layer forming method)
Immersion plating is performed by immersing in a plating bath each containing 0.2 g / l palladium chloride + 10 g / l stannous chloride + 100 ml hydrochloric acid at a bath temperature of about 40 ° C. for about 2 minutes. Thereafter, the tin is removed by washing with a sulfuric acid aqueous solution at a temperature of 40 ° C. and a concentration of 100 g / l for about 2 minutes. Washing with water during this time is required. The Pd concentration (purity) and film thickness of the Pd or Pd alloy layer are controlled by adjusting the number of plating treatments, metal ion concentration, or immersion time.

(Ni-P plating method)
In order to obtain a Ni-P plating film, electroplating is acceptable, but the Ni-P plating film is preferably electroless plating from the viewpoint of uniformity of film thickness (film thickness distribution). Hereinafter, suitable electroless plating conditions will be described.

After the pretreatment or after forming the intermediate layer (underlying layer) that is selectively provided, a Ni-P plating film is formed by an electroless plating method. The bath composition of the plating bath is, for example, nickel sulfate 30 (range 10-50) g / l, sodium phosphinate 20 (range 10-30) g / l, NH, so as to be within the above-described plating film composition range. A compound containing ₄ groups (for example, diammonium hydrogen citrate) 50 (range 30-70) g / l, and, as an additive, sodium acetate, succinic acid, citric acid, malic acid or their sodium salts And about 10 g / l of an organic additive. A relatively high temperature of 80 to 90 ° C. is employed as the bath temperature. The optimum pH of the bath is in the neutral range of 6-7.

  The titanium base material after the formation of the intermediate layer (film) is immersed in a plating bath whose composition, temperature, and pH are controlled for a predetermined time. The composition and thickness of the Ni-P are controlled by adjusting the composition, temperature, pH, or immersion time of the Ni-P electroless plating bath.

(Cr plating)
Cr plating can be performed by a known method. A plating bath containing about 100 to 500 g / l of chromic acid, 3 to 7 g / l of sulfuric acid, 3 to 7 g / l of trivalent chromium, 6 to 10 g / l of organic sulfonic acid, Electroplating is performed at about 55 ° C. and an energization amount of about 40-60 A / dm ² . The film thickness of the Cr plating is controlled by adjusting the composition and temperature of the plating bath, or the energization amount and energization time.

(Titanium base)
As the type of the titanium base material that is the material (base material) of the film, known pure titanium, α, β titanium alloy, and the like can be appropriately selected and used according to required characteristics and mechanical properties.

Examples of the present invention will be described below.
A disk material of 44 mmφ × 5 mm for a normal wear test was manufactured from a Ti-6% Al-4% V plate, and used as a titanium substrate.

  Using these titanium substrates as materials to be treated, an intermediate layer and an upper layer: a Ni-P electroless plating film were selectively formed by the above-described method and conditions. Among these, the Ni—P electroless plating film was formed in common with each example so that the average film thickness was 10 μm or 75 μm (± 0.5 μm). The hard Cr plating was also selectively formed on the upper layer of the Ni-P electroless plating film. Further, when a Ni or Ni alloy layer was formed as the intermediate layer, # 100 glass beads were sprayed and roughened on the surface of the Ni or Ni alloy layer.

The film properties of each of the produced disk materials were measured as follows. These results are shown in Table 1.
(Middle layer)
The thickness of each layer of the Ni layer and the Pd layer.
Ni and Pd purity of Ni layer or Pd layer.
(Ni-P electroless plating film)
Ni amount, P amount, NH ₄ ⁺ (NH ₄ group) amount, crystallite size,
XRD measurement peak intensity ratio: Ni (111) / Ni (200).

Each of these film properties was measured by the following methods.
(Ni-P electroless plating film)
ICP emission spectroscopy was used for the Ni and P amounts of the Ni-P plating film, and ion chromatography was used for the NH ₄ ⁺ amount. However, these analyzes were performed on samples with a plating film, and pure titanium was used as a standard substrate. In addition, elements such as Cu, Zn, and Al from the underlayer obtained by measurement were excluded from the calculation for calculating the Ni, P amount and NH ₄ ⁺ amount.

  The crystallite size of the Ni-P plating film is measured on the Ni (200) diffraction surface using the characteristic X-ray Cu-Kα (wavelength: 1.54 mm) from the sample surface with an X-ray diffractometer. ) Was included in the following Scherrer equation. For the integral width, a value corrected by the Cauchy function was used. D = K · λ / βcos θ, D: crystal size (Å), K: constant (1.05), λ: measured X-ray wavelength (Å), β: broadening of diffraction line due to crystallite size, integration Width (radian), θ: Black angle of diffraction line.

  The XRD measurement peak intensity ratio of the Ni-P plating film was obtained by using characteristic X-ray Cu-Kα (wavelength: 1.54 mm) with an X-ray diffractometer from the same sample surface with the plating film attached. The peak intensity was obtained from the peak heights of {111} and {200} from the X-ray diffraction chart, and Ni (111) / Ni (200) was calculated.

(Middle layer)
The amount of Ni in the Ni layer and the amount of Pd in the Pd layer were quantitatively analyzed at a depth at which each metal amount peaks from the concentration distribution in the depth direction of Auger electron spectroscopy.

(Thickness)
The thickness of each layer or film was determined by observing the cross section with a 500 times SEM (scanning electron microscope) at each 10 locations to determine the average film thickness of each layer or film.

(Characteristics of Ni-P electroless plating film)
In addition, the properties of the produced disk material films, such as hardness, toughness and plating tensile stress, were measured as follows. These results are shown in Table 1.

Hardness: Vickers hardness was measured from a cross section at a load of 50 gf.
Toughness: Evaluated at the minimum load at which cracking occurs in the film by indentation of the Vickers indenter. However, if no crack occurred at the maximum load (50kgf) of the device, it was set to> 50kgf.
Plating tensile stress: Plating tensile stress was measured with a spiral plating stress meter.

In addition, the wear resistance of each disk material surface (coating) produced was evaluated under the following conditions. These evaluation results are also shown in Table 1.
(Abrasion resistance evaluation)
As abrasion resistance test 1, shot blasting (5 kg / cm2, glass base # 100, sprayed from 10 cm directly above) causes the Ni-P electroless plating film of about 10 μm in each example to wear or peel, exposing the substrate. The time until was measured. The evaluation of this test was as follows. > 60 sec: A, 30-60 sec: A, 10-30 sec: Δ, <10 sec: ×.

As the abrasion resistance test 2, a ball-on-disk test was performed. The test conditions were: SUJ2 as the mating ball, load 1 kgf (calculated from maximum contact surface pressure 100 kgf / mm ² -hertz pressure), no lubrication, sliding speed 1 m / s, sliding distance 1 km ( mg). The evaluation of this test was as follows. <◎ at 3 mg, ○ at 3 to 6 mg, Δ at 6 to 10 mg, and × at> 10 mg.

As can be seen from Table 1, Invention Examples J to V have compositions and crystallite average sizes satisfying the scope of the present invention in the Ni-P plating film. For this reason, the hardness of the Ni—P plating film as plated is 500 Hv or more, the toughness is 1 kgf or more, and the plating stress is 5 kgf / mm ² or less.

  As a result, as can be seen from Table 1, Invention Examples J to V have no evaluation x in all wear resistance tests, and can be applied as wear-resistant titanium materials or machine parts using the same. I understand.

  On the other hand, in Comparative Examples A to G, in the Ni—P plating film, any of the Ni—P plating composition, the crystallite average size, and the intermediate layer is outside the scope of the present invention.

Comparative Example A had no intermediate layer and could not be formed.
In Comparative Example B, the amount of Ni is too small in the Ni-P plating composition.
In Comparative Example C, the amount of P is too small in the Ni-P plating composition.
In Comparative Example D, the NH ₄ group content is too small in the Ni—P plating composition.
In Comparative Example E, the NH _{4 group} content is too large in the Ni—P plating composition.
In Comparative Example F, the amount of Ni is too small in the composition of the Ni alloy film of the intermediate layer.
In Comparative Example G, the amount of Pd is too small in the composition of the Pd alloy film of the intermediate layer.
As a result, Comparative Example B has a low hardness, and Comparative Examples C to G have a crystallite size that is out of the present invention, and has low toughness or high plating stress.

  In Comparative Examples H and I, the Ni-P plating composition, the average crystallite size, and the intermediate layer are all within the scope of the present invention. As described above, Ni-P plating is performed on the Ni or Ni alloy intermediate layer. In such a case, the crystallite size increases depending on conditions.

  As a result, it can be seen that Comparative Examples A to I are inferior in wear resistance and cannot be applied as wear-resistant titanium materials or machine parts using the same.

Among Invention Examples, Invention Example J has a Ni amount close to the lower limit value in the Ni-P plating composition. In invention example K, the P amount is close to the lower limit. Invention Examples L and M have NH ₄ group amounts close to the lower limit and the upper limit. In Invention Examples N and O, the amounts of Ni and Pb components in the intermediate layer are close to the lower limit values. Invention Example P is Ni-P plating on Ni or Ni alloy intermediate layer, and the average crystallite size is close to the upper limit.

  For this reason, these invention examples have a Ni-P plating film hardness as plated as compared with Invention Examples Q and T-V which satisfy these Ni-P plating compositions and intermediate layers near the intermediate value. It tends to be either low, low toughness, or high plating tensile stress. Therefore, abrasion resistance is also inferior compared with invention example Q and TV.

  Therefore, these results support the critical significance of the Ni-P plating composition, the average crystallite size, and the intermediate layer in the present invention with respect to wear resistance.

  Furthermore, it can be seen that the wear resistance is further improved by applying a Cr layer as in Invention Examples R and S.

  As described above, according to the present invention, it is possible to provide a wear-resistant titanium material subjected to Ni-P plating having excellent wear resistance and fatigue characteristics, and a mechanical component made of titanium material. As a result, it is possible to expand the application of the wear-resistant titanium material to applications where it is desired to reduce the weight of wear-resistant parts, or applications that require wear-resistant parts with higher reliability including wear resistance.

Claims (5)

A titanium material provided with a Ni-P plating film, wherein the Ni-P plating film is in mass%, Ni: 85% or more, P: 1 to 5%, NH ₄ group: 0.1 to 1%. A Ni-P plating film having a crystallite average size of 1 to 5 nm in a Ni-P plating film structure analysis by an X-ray diffraction method, and the titanium material and the Ni-P plating film At least one of a Ni or Ni alloy layer with Ni of 99% or more and a Pd or Pd alloy layer with Pd of 90% or more is formed on the interface, and the Ni-P plating film is plated. A wear-resistant titanium material having a hardness of 500 Hv or more as it is.   The measurement peak intensity ratio Ni (111) / Ni (200) of Ni (111) and Ni (200) in the Ni-P plating film structure analysis by the X-ray diffraction method is 0.3 to 0.5. Item 2. The wear-resistant titanium material according to Item 1. The wear-resistant titanium material according to any one of claims 1 to 2, wherein a plating tensile stress of the Ni-P plating film is 5 kgf / mm ² or less.   The wear-resistant titanium material according to any one of claims 1 to 3, wherein the Ni-P plating film is electroless plating.   The wear-resistant titanium material according to any one of claims 1 to 4, wherein a hard Cr plating is further applied to an upper layer of the Ni-P plating film.