JPS6299450A - Sliding member - Google Patents

Abstract

PURPOSE:To obtain an inexpensive sliding member having superior wear resistance even under high surface pressure, a weak attacking property to an opposite member and superior seizing resistance by forming a thermally sprayed Mo-Al alloy or Cu alloy layer having a high Mo content as an upper layer when a thermally sprayed Mo-Al alloy or Cu alloy layer having a low Mo content is formed on a base material to obtain a sliding member. CONSTITUTION:A thermally sprayed low-Mo layer I consisting of 2-30wt% Mo and the balance Al alloy or Cu alloy is formed on the surface of the sliding part of a base material 1 as usual. A thermally sprayed medium- or high-Mo layer II of >=5mum thickness consisting of 30-95wt% Mo and the balance Al alloy or Cu alloy is formed on the lower layer I.

Description

[Detailed description of the invention] (Industrial application field) [.

1. The present invention relates to a sliding member that has excellent wear resistance and seizure resistance even under high surface pressure.

1 (Prior art) l In recent years, demands for higher output and lower heating costs for automobiles □1 - bommss, "9"""'"-'1
1 [Synchronizer ring inner surface, cylinder lychee inner bamboo
Surfaces, piston rings, transmission friction plates, etc. are increasingly being used under high surface pressure. In such a case, the sliding part is likely to cause seizure or abnormal wear, so it is required that the performance of the sliding member be improved to 1% in seizure resistance and wear resistance more than ever. Among sliding parts, for example, regarding shift forks, the pawls have traditionally been treated with induction hardening, hard chrome plating, and aluminum bronze spraying, but these methods are no longer applicable under the harsh sliding conditions of recent times. be.

For this reason, a method of improving the sliding characteristics by spraying a material with excellent sliding characteristics on the surface of the sliding part by plasma spraying or the like is widely used. Conventionally used thermal spray materials include, for example, Moripude 7 (MO) and iron-chromium (MO).
Fe-Cr), iron-carbon (li'e -0,8C; carbon content 0.8%), 7A/minatetania (A I
t oh −T t ot ), and the like.

However, when using the above-mentioned conventional thermal spray materials, there are the following problems. That is, in Mo thermal spraying, MO has resource problems and is extremely costly.

In Fe-Cr thermal spraying, the thermal spraying material itself has excellent wear resistance, but it is highly aggressive toward the mating material and tends to wear the mating material.

Moreover, Fe-0,8C thermal spraying has a problem with the wear resistance of the thermal spraying material itself. Furthermore, thermal spraying using ceramic powder, such as Al2O,-Tie and thermal spraying, has excellent wear resistance, but is highly aggressive towards the mating material, so it tends to wear out the mating material, and it also tends to cause damage to the metal base material. It is difficult to obtain sufficient adhesion,
Parts that are subjected to shock loads, vibrations, etc. are likely to separate from the metal base material.

In addition, as a recently known technique, a sliding member has been proposed which is characterized by providing a thermally sprayed layer on a base material, which is composed of 2 to 30% by weight of molybdenum and the remainder aluminum alloy or copper alloy. (Refer to Japanese Patent Publication No. 58-10986).

The member has a hardness Hv: about 100 to 200 hypereutectic ht
-s as a single sprayed layer on an At alloy sprayed layer such as H
v: M having a hardness of about 500 to 600 and good seizure resistance.

By forming a sprayed layer containing 2 to 30% by weight of MO
I was trying to get the same performance as a single layer, but I was unsuccessful. Automobile parts such as shift forks and synchronizer rings obtained using such members exhibit excellent wear resistance and seizure resistance under normal sliding conditions, that is, when the surface pressure is approximately 2 Kyf/wx" or less. However, this Case 2 or 3
At an MO content of 0% by weight, kl-8
The distribution state is such that Mo (3) is scattered in the i-alloy (2), and the sliding conditions of higher surface pressure that will be required in the future, for example, as shown in performance test 2 described later, the surface pressure of 5 cm / 7w2
, under the condition that the synchro rotation speed is 600 Orpm,
It has been found that the sliding member described above has sufficient wear resistance. From the observation of the sliding surface in the above test, as shown in FIG. 4, the surface of the sprayed layer 1c Mo (3) was exposed.

Although the sprayed surface remains, the At-8t (2) with low hardness, which occupies most of the surface layer before sliding (4), has been scraped off, and the resulting unevenness of the surface layer reduces the coefficient of friction. It was found that it caused

(Problems to be Solved by the Invention) The present invention is intended to solve the problems in the above-mentioned prior art, and its purpose is to
(2) The purpose of the present invention is to provide an inexpensive sliding member that has excellent wear resistance even when placed under a high surface pressure of up to 2, is less aggressive to mating materials, and has excellent seizure resistance.

(Means for Solving the Problems) That is, the sliding member of the present invention has a thermal sprayed layer (2 to 30% by weight of molybdenum (Mo) on the surface of the sliding part of the base material, the balance being an aluminum alloy and a copper alloy). On top of the "lower layer" (hereinafter referred to as "lower layer"), another thermal sprayed layer (hereinafter referred to as "upper layer") having a thickness of at least 5 μm and consisting of 30 to 95% by weight of MO and the balance aluminum alloy or copper alloy is provided. It is characterized by

The present invention will be explained in more detail below.

Aluminum alloys used in the present invention include aluminum-silicon (At-8i) alloys and aluminum-lead (At-Pb) alloys, but in particular hypereutectic At
-8i alloy is preferred. Further, as the copper alloy, an aluminum bronze alloy or a phosphor copper alloy is used, and an aluminum bronze alloy is particularly preferred.

In order to adjust the thermal spraying material, each powder thermal spraying material (10
0 to 400 meshes) may be separately supplied to a thermal spraying device and sprayed at the same time to form the desired thermal sprayed layer, or the matrix material and M may be added in advance before being supplied to the thermal spraying device.

It may be carried out using a mixture of MO powder or a composite material in which MO powder is adhered to the surface of a matrix material. In order to maintain the surface pressure during sliding of the base material, a surface roughness of about 25 μRZ or more is required, so the matrix material for the lower layer is preferably an At-8i material having a roughness of 30 to 70 μRZ after thermal spraying.

The thermal spraying method may be any of the gas wire method, gas powder method, plasma method, and explosion method. In these cases, the upper MO
It is necessary to thermal spray to create a difference between the Mo content and the Mo content in the lower layer, but this requires the above-mentioned matrix material and Mo content.
'This can be achieved by changing the supply amount ratio of the powders, by changing the mixing ratio of both powders midway through, or by using a composite material in which the amount of Mo powder attached to the surface of the mesh matrix material is changed.

Iron-based alloys such as cast iron and steel, or light alloys such as aluminum alloys are used as the base material, but the surface of these base materials is usually
Since there are irregularities of about 0 to 50 μm, the thickness of the sprayed layer (upper layer and lower layer) may be exposed if it is not sprayed to a sufficient thickness, and the adhesive force between the sprayed layer and the substrate will be weakened. Saha 50
The thickness is preferably µm or more. It was also found that the thickness of the upper layer should be 5 μm or more in order to maintain wear resistance and seizure resistance at high surface pressures. This means that by providing a lower layer with a low MO content, the upper layer with a high Mo content can be made considerably thinner, which means that the overall amount of MO used can be reduced, which is advantageous in terms of resources and costs. Become.

Regarding the MO content, if it is less than 30% in the upper layer, it will not be able to withstand the compressive stress due to high surface pressure of 3 to 6 Kqf/1m", and the wear resistance and seizure resistance will decrease. In this case, the wear of the phase member increases significantly. Therefore, the MO content of the upper layer is set to 30 to 95 inches. In some cases, the upper layer sinks into the lower layer due to high compressive force, and the wear resistance effect of the upper layer is no longer sufficient, so the hardness of the lower layer Hv
:200 to 250 is preferable, and for that purpose, the MO content in the lower layer must be 2 to 30.

From the above, the hardness of the upper layer is HV: 250 to 50.
0, and the assumed cross section is as shown in Figure 2, consisting of the lower layer (I) in which Mo (3) is distributed at a low rate in the At-8i alloy (2), and the upper layer (ω) in which Mo (3) is distributed at a high rate in the At-8i alloy (2). The sprayed layer becomes the base material (
1) A sliding member is obtained.

The present invention will be explained in more detail with reference to Examples below. A performance test for confirming the effects of the present invention is also listed.

Example 1 The outer surface of a cylindrical test piece made of steel (equivalent to JIS standard 5UJ2) with an outer diameter of 35 mm, an inner diameter of 30 mm, and a width of 10 mm was coated with the mixture ratio of MO as shown in Table 1. changed within the range. A cylindrical test piece coated with Cr was also prepared as a comparison material. Thermal spraying was carried out under the following conditions by preheating the base material to 150-200 DEG C. after degreasing the base material and pre-treating it for shot blasting.

Gasket N, (7°08t/min) 10He (4,71/
), the spray distance was 120 m, and the powder feed rate was 50 m.
It was set to V minutes. Still use it as a test piece on the other side5
A plate-shaped test piece of UJ2 was used. A 3M type plasma spraying device manufactured by METCO was used as the thermal spraying device.

As described above, test thermal sprayed ring material B-K and Cr metal coating ring material A to be subjected to the following performance test 1 were obtained.

Performance Test 1 Test pieces A to K obtained in Example 1 were subjected to an LFW (friction and wear) test, and the amount of wear between the thermal sprayed layer and the mating material of each test piece was measured. A plate-shaped test piece of 5UJ2 was used as the mating material, the wear conditions were a surface pressure of 5 hf/1 m21 cylindrical test piece, and a rotation speed of 200 rpm, and transmission oil was used as the oil, and measurements were taken 1 hour after the start of the test. The results of this wear test are shown in FIG. In FIG. 1, the numbers below the bar graph indicate the MO content in the sprayed layer.

The comparative Cr-plated product A developed seizure after about 30 minutes, whereas the thermal sprayed product B- did not experience seizure until the end of the test (until 1 hour later).

As can be seen from Figure 1, specimens with a Mo content of less than 30% (B-D) exhibited significantly more wear, and as the MO content increased, the wear decreased, but with 100% Mo
In the wholesale of O-type products, the wear of the mating material increases significantly.

Furthermore, when the cross section of the sprayed layer was observed under a microscope after the test, it was found that the amount of Mo was low.
At C-E, where the Mo addition rate was high, the At-8i layer was significantly scraped off, resulting in a smooth surface with many parts of the MO layer exposed on the surface, whereas at F-J, where the Mo addition rate was high, Most of the unevenness of the initial sprayed layer remained.

Example 2 A plurality of cylindrical test specimens similar to those of Example 1 were prepared, and one was coated with At
-23.9%Si alloy powder only, and At on the other side.
A lower layer was formed by spraying a -23,9-Si:MO (5:1) mixed powder to a thickness of 100 μm. Then, At-23,9%Si:MO(1
:1) The mixed powder was sprayed to a thickness of 100 μm. Note that other thermal spraying conditions are the same as in Example 1. In this way,
Lower layer 0chi.

Two test specimens were obtained: a comparative thermal sprayed ring material (L) having a 50-inch MO-containing sprayed layer in the upper layer and a thermal-sprayed ring material (M) of the present invention having a 20% Mo-containing sprayed layer in the lower layer and 50 inches in the upper layer. Ta.

Performance Test 2 A test similar to Performance Test 1 was conducted using the thermal sprayed ring material obtained in Example 2 and M. As a result of the wear test, the wear amount of the comparative ring material was 11 cm, whereas the ring material of the present invention had a wear amount of 5 cm, which was 50% of that shown in Example 1.
Almost the same value as the result of Mo-containing product G was obtained.

In other words, the lower layer is made of At-8i alloy alone (hardness Hv: about 100-150), while the lower layer is made with Mo added (hardness Hv: about 100-150).
Hardness Hv: 200 to 250) was found to have better wear resistance.

Example 3 A containing 10% Mo in the lower layer and 70% in the upper layer
The spraying conditions were changed to form a 4-23% Si sprayed layer, and the thickness of the upper layer was as shown in Table 2 under the condition that the total thickness of the upper and lower layers was 2007'm. In addition, in order to test how thick the upper layer is required when forming a sliding member by forming a 9-inch Si sprayed layer (200 μm in total) in Table 2, Example 3 was conducted. A test similar to Performance Test 1 was conducted using the prepared test piece N-T. The results are shown in Figure 3. The number below the bar graph in FIG. 3 represents the thickness of the upper layer (μm). As can be seen from the figure, those with an upper layer thickness of 5 μm or more (P-T) showed almost the same good wear resistance, but N and 0
If the thickness was less than 5 μm, the effect of the upper hard sprayed layer could not be seen.

Example 4 A sprayed layer having a thickness of 200 μm was formed on the sliding surface of the synchronizer ring with the gear in the same manner as in Examples 1 to 3.

The sprayed layer composition used At-23,9%Si alloy as the matrix material, and the lower layer (thickness: 170 mm)
pm) VCl 0%, upper layer (thickness 30 μm) containing 50% MO (1), full layer (thickness 200 pm) K1
A sample containing 0% Mo (U) was prepared.

Performance test 4 Sliding test parts obtained in Example 4 1. If each surface pressure is 5Kyf/■3% synchronized rotation fi6000rp
It was subjected to a synchro shift durability test. As a result, it was found that the product (2) of the present invention showed no abnormality after 1000 shifts, but the friction coefficient suddenly decreased after about 10 shifts for the comparative product (1), and a shift noise occurred. Due to this, At-23tssi is used as the matrix material at 1/-1
When forming a sprayed layer with a thickness of 200 pm, the entire layer is coated with 1
0ch M.

The lower layer (thickness 170 μm) is 50 cm and M
This shows that a two-layer structure with different O content clearly reduces wear.

(Effects of the Invention) Performance tests 1, 2, and 3 each indicate the necessity of a 30-inch or more MO-containing upper layer, a low Mo-containing lower layer, and an upper layer thickness of 5 μm or more, which are the constituent elements of the present invention.

In addition, in performance test 4, the upper limit of Mo content in the upper layer was 95%.
It suggests that.

As is clear from the results of the performance tests 1 to 4, the sliding member of the present invention exhibits wear resistance, seizure resistance, and non-aggressiveness against mating members even under severe surface pressure of 5 kgf/wm2. Therefore, the present invention is applicable to various sliding parts that are required to be subjected to higher blood pressure than before, such as piston rings, cylinder bores, pistons, near compressor parts, etc.
When used in piston rings, shift forks, synchronizer rings, etc., it has wear resistance, seizure resistance, corrosion resistance,
Effect of improving various physical properties of heat resistance

[Brief explanation of drawings]

FIG. 1 is a graph showing the wear resistance of the sliding member when the MO content in the sprayed layer (thickness: 200 μm) was changed. FIG. 2 is a Shino-style cross-sectional view of the sprayed layer of the sliding member of the present invention. Figure 3 shows the lower layer (10% MO content) and upper layer (70% MO content).
It is a graph showing the wear resistance of the sliding member when the thickness of the upper layer is changed under the condition that the total thickness of the content) is 200 μm. FIG. 4 is an enlarged cross-sectional view of the HT-ST sprayed layer containing Mo2 to 30% after sliding under high surface pressure. In the mouth ~ 1... Base material 2... At-8i
Alloy 3...Mo 4...Sliding surface! ...Low Mo content lower layer...Medium/high Mo content sprayed layer Alphabet...Test piece symbol Number below bar graph...Top layer thickness in Figure 3 μm), the first
The figure shows the MO content (%) in the sprayed layer. Patent Applicant: Toyota Motor Corporation Figure 1 8K) Upper Nohi (1 middle power request) Fang 2 figure ■...However, MO included Wa Elephant Shooting ■... + UMo included Fuda Rock Shooting 1 Fang 3 Tsurikan. Test 1 Otsu Momo 5 P-m-) 'f, 5Q RS T Climb (m9) Cheer 4 Figure 3・-Mo 4...Boar driving surface 1 side tusk 5 Figure

Claims (1)

[Claims] A sprayed layer consisting of 2 to 30% by weight of molybdenum and the remainder of the aluminum alloy or copper alloy is provided on the surface of the sliding part of the base material, and a sprayed layer of 30 to 95% by weight of molybdenum and the balance of the aluminum alloy or copper is further provided on this sprayed layer. A sliding member characterized in that it is provided with a thermally sprayed layer with a thickness of 5 μm or more made of an alloy.