JPS5848023B2 - Manufacturing method of wear-resistant iron-based sintered alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a ferrous sintered alloy with good initial break-in and improved wear resistance.

In order to increase the wear resistance of sliding parts, supplying lubricating oil to the sliding surfaces, increasing the hardness of the metal material of the parts, or dispersing lubricating components such as graphite in the metal material structure. This is commonly done, but
Oil films on the sliding surfaces of parts that slide at high temperatures and high speeds tend to break off, often resulting in increased wear or seizure.

The applicant previously proposed a method for producing a sintered alloy with high oil retention and low wear that can be used under such severe conditions, and developed a 200-mesh or lower sintered alloy with a silicon content of 1 to 2%. We have proposed a method for producing wear-resistant iron-based sintered alloys in which a green compact containing erosilicon mixed in raw material powder is sintered so that the silicon remains in granular form without being diffused. No. 89556 (Japanese Unexamined Patent Publication No. 50-38611), title of the invention, wear-resistant sintered alloy and method for producing the same.

(hereinafter referred to as the "prior invention"). The present invention relates to an improvement of the manufacturing method of the prior invention, and aims to provide a method for manufacturing iron-based sintered alloys with even better initial fitting and further improved wear resistance. This relates to a method in which a green compact is produced by a method similar to the above method except that the powder is blended into the raw material powder so that the powder becomes 10%, and the green compact is sintered to obtain a sintered compact.

Next, an example will be described.

Sprayed iron powder under 100 mesh, ferrosilicon (Si grade 50%) under 200 mesh, electrolytic copper powder under 325 mesh, natural graphite under 10 microns, zinc stearate (indicated by Zn-st) under 10 microns. Raw material powders were blended using the following two types of blending ratios.

Sample A: 1, 2% C, 3% Si, 3% Cu, 0.7
5% Zn-st, balance Fe Sample B: 1.2% C1 10% Si, 7% Cu, 067
After mixing 5% Zn-st1 and balance Fe, the nominal diameter was 7 at a pressure of 5t/Ci.
3. Oi4 width 2. Pressed using a free-form mold with a thickness of 3.0 mm and a thickness of about 700 mm.
After pre-sintering for 20 minutes at ℃, an endothermic gas (24%Co
, 31% H2, 0.30-0.32% CO2, N2 remaining)
Sintering was carried out at 1120° C. for 50 minutes.

The sintered body thus obtained has a nominal diameter of 73.0ii and a width of 2
．． 0 mm, thickness 3. Processed into 0 mm piston ring, Nissan A-12 engine, 1 1 7 1
cc, maximum output 68PS/6,00O r. p. An actual machine test was conducted by installing it on the M.

As a comparison material, a cast iron piston ring plated with chrome was used (shown as sample C).

The test conditions are as follows.

6.00O r. p. m, 4/4Load oil, water temperature:
900C gasoline: Unleaded gasoline test results are shown in Figure 1.

The horizontal axis shows the operating time, and the vertical axis shows the outer circumferential wear amount (microns), and curves A, B, and C show the results of samples A, B, and C, respectively.

For comparison, 1. shown in the aforementioned Japanese Patent Application No. 4889556
Similar test results (shown as curve D) for a piston ring with 0.5% Si, 1.4% C, and 3% Cu are shown.

As can be seen from curves C and D in this figure, 1 of the prior invention
．． 0.05% Si, material D has a greater amount of wear than chrome-plated material C at the beginning of operation, but as the operation time progresses, the increase in wear amount gradually decreases, and the amount of wear decreases to about 260% Si. After ~270 hours, the two become the same, and as the operation continues beyond that, the 1.05% Si test piece shows less wear than the chromium-plated cast iron, and the initial fit is better, and once the operation is continued, the amount of wear becomes smaller. Once the material is blended in, the wear rate decreases and it exhibits excellent wear resistance, but in the sintered alloy according to the present invention, curves A and B
As shown in , the initial conformability is even better, and the amount of wear is less than that of the chromium-plated material after about 50 hours for the 3% Si material and about 100 hours for the 10% Si material. It can be seen that the initial fit is much improved compared to the alloy, and the amount of subsequent wear is also small, indicating that the wear resistance is even more excellent.

The reason why the sintered alloy of the present invention is excellent in terms of wear resistance is that the sintered alloy of the present invention is superior in terms of wear resistance.
The M content is blended into the raw material powder to be 3 to 10%, and the green compact using this is heated and sintered at 1120°C in the same manner as the method of the applicant's earlier invention. In addition, the blended Huekou silicon particles do not diffuse into the surrounding base metal during sintering, and remain in granular form as in the case of the method, and the hard Huekou silicon particles and the base do not diffuse into the surrounding base metal. It is thought that this is due to the fact that the area ratio is a value more suitable for reducing initial wear and subsequent wear.

As described above, in the sintered alloy of the present invention, the sintering temperature is set to 1150° C. or lower in order to sinter the blended silicon particles so as to remain as they are.

When this temperature increases, it becomes difficult to suppress the diffusion of Sr even if the sintering time is shortened, and the variation in the amount of undiffused Si increases.

FIG. 2 shows the results of an abrasion resistance test using a Hayama tester, in which samples A and B had the same formulation as above, and sample E had the following formulation.

Sample E: 1.2%C1 12%Si, 7%Cu, 0.7
5% Z n-s t After mixing each of these mixed powders, 5t/ffl
After molding to 10 x 10 x 70 mm under pressure and sintering in the same manner as above, 5 x 5 x 301! jl! The sample was polished to 0.2 emery paper and used for testing.

The comparative material (sample F) is cast iron for piston rings.

According to the figure, sample A containing 3% Si has clearly less wear than the comparative material and has excellent wear resistance, but
lo% of sample B is roughly equivalent to the comparative material, 8112
% sample E has a greater amount of wear than the comparative material.

From this test result, it is considered that the upper limit of the Si content is preferably 10%.

As explained above, the sintered alloy of the present invention is made by mixing ferrosilicon of 200 mesh or less into raw material powder so that the Si content is 3 to 10%, and sintering it to prevent diffusion. As a result of the improved area ratio of the hard particles to the matrix, the initial fit is good even under harsh sliding conditions, and the amount of subsequent wear is lower than that of conventional chrome-plated materials.
The amount is significantly smaller than that of the sintered alloy produced by the method of the prior invention, and exhibits excellent wear resistance.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the results of an actual engine test, and FIG. 2 is a bar graph showing the results of a wear resistance test using a Hayama wear tester. Curves A, B...The merits of the sintered alloy according to the present invention,
Curve C: Performance of a cast iron piston ring plated with chrome, Curve D: Performance of a sample containing ferrosilicon with a Si content of 1.05% , Curve E...Si content is 12%
The results of the sample containing Hueguchi silicon so that the result, curve F... The merits of cast iron for piston rings.

Claims (1)

[Claims] 1. Ferrosilicon of 200 mesh or less is mixed with raw material powder so that the silicon content is 3 to 10%, molded, and then heated to 1150°C or less in a reducing atmosphere and sintered. A method for manufacturing a ferrous sintered alloy that has good initial fitting and improved wear resistance.