Valve guide pipe material suitable for methanol engine and preparation method of valve guide pipe material

Abstract

The invention discloses a valve guide pipe material suitable for a methanol engine and a preparation method of the valve guide pipe material. The material comprises the following element raw materials in percentage by mass: 0.6%-1.2% of C, 0.5%-3.0% of Mo, 1.0%-5.0% of Cr, 2.0%-5.0% of Ni and the balance of Fe. The preparation method comprises the following steps: ball-milling and uniformly mixing raw material powder in proportion; carrying out compression molding on the mixed powder on a pressing machine; carrying out high-temperature sintering on the formed blank in a sintering furnace; performing vacuum oil immersion treatment; and machining to obtain a finished product. The corrosion-resistant and high-temperature-resistant wear-resistant performance of the powder metallurgy guide pipe is improved, and the powder metallurgy guide pipe can cope with severe engine working conditions and particularly can be matched with methanol engine working conditions.

Description

Technical Field

[0001] The invention relates to the field of engines, and in particular to a valve guide material suitable for a methanol engine and a preparation method thereof. Background Art

[0002] Methanol fuel, as a clean energy source, can realize carbon cycle, which is different from traditional fuel. Fuel methanol contains a small amount of organic acids, such as formic acid, methyl formate and aldehydes, etc. The higher the temperature, the more serious the metal corrosion. As one of the core components of the engine valve mechanism, the valve guide is in direct contact with methanol fuel and will be severely corroded at high temperatures. The existing system powder metallurgy valve guide is difficult to meet the high temperature wear requirements of methanol engine under corrosive conditions. Summary of the invention

[0003] The object of the present invention is to provide a valve guide material suitable for a methanol engine and a preparation method thereof, which improves the corrosion resistance and high temperature wear resistance of the powder metallurgy guide and can cope with harsh engine operating conditions, especially matching methanol engine operating conditions.

[0004] In one aspect of the present invention, a valve guide material suitable for a methanol engine is provided. According to an embodiment of the present invention, the material comprises the following element raw materials in mass percentage: 0.6%-1.2% C, 0.5%-3.0% Mo, 1.0%-5.0% Cr, 2.0%-5.0% Ni, and the balance is Fe.

[0005] In another aspect of the present invention, the present invention provides a method for preparing a valve guide material suitable for a methanol engine. According to an embodiment of the present invention, the preparation method comprises the following steps:

[0006] (1) ball milling the raw material powders according to the proportion and mixing them uniformly;

[0007] (2) Pressing the mixed powder into a shape on a press;

[0008] (3) sintering the formed blank at high temperature in a sintering furnace;

[0009] (4) subjecting the high-temperature sintered material to vacuum oil immersion treatment;

[0010] (5) Machining the vacuum oil-impregnated material into a finished product.

[0011] In addition, the method for preparing a valve guide material suitable for a methanol engine according to the above embodiment of the present invention may also have the following additional technical features:

[0012] In some embodiments of the present invention, in step (1), ball milling is performed for 0.5-2 hours, and the particle size of the raw material after ball milling is ≤80 microns.

[0013] In some embodiments of the present invention, in step (2), the molding density is 6.7-7.0 g / cm3, and the press tonnage is 25-35 T.

[0014] In some embodiments of the present invention, in step (3), the sintering temperature is 1060-1100° C., and the sintering time is 1-2 h.

[0015] In some embodiments of the present invention, in step (4), the vacuum degree of vacuum oil immersion is 100 Pa, the oil immersion temperature is 90° C., and the vacuum oil immersion time is 30-60 min.

[0016] In some embodiments of the present invention, in step (5), a cemented carbide tool is used, the tool speed is 800-1500 r / min, and the tool feed is 40-100 mm / min.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention uses carbon powder, iron powder, nickel powder and molybdenum powder to prepare FeNiCrMo alloy matrix powder by ball milling. The alloyed matrix powder prepared by the formula and process has good formability, uniform structure and good corrosion resistance and wear resistance. Ni and Cr elements construct a corrosion-resistant system, Mo element refines the grains, and the FeNiCrMo matrix alloyed by ball milling has good corrosion resistance and wear resistance, and can cope with the working conditions of methanol engines. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example 1

[0021] A valve guide material suitable for a methanol engine comprises components in the mass percentages shown in Table 1.

[0022] Table 1: Components of valve guide materials suitable for methanol engines in Example 1

[0023] element C Cr Mo Ni Fe Content wt% 0.7 1.5 0.8 2.4 94.6

[0024] A preparation method for a valve guide material suitable for a methanol engine has the following process: ball milling mixing → pressing molding → high temperature sintering → vacuum oil impregnation → machining, specifically comprising the following steps:

[0025] (1) ball milling the raw material powders according to the proportion for 1.5 hours to mix them evenly, and the particle size of the raw material after ball milling is ≤80 μm;

[0026] (2) Press the mixed powder into a mold on a press with a molding pressure of 26T;

[0027] (3) Sintering the formed blank in a sintering furnace at a high temperature of 1065°C for 1.5 h;

[0028] (4) Vacuum immersion treatment: vacuum degree 100Pa, immersion temperature 90℃, vacuum immersion time 45min;

[0029] (5) The finished product is machined using a carbide tool, wherein the tool speed is 1200 r / min, the tool feed is 60 mm / min, and the outer diameter of the finished product is 15.1 mm, the inner diameter is 8.45 mm, and the length is 80.3 mm.

[0030] Example 2

[0031] A valve guide material suitable for a methanol engine comprises components in the mass percentages shown in Table 2.

[0032] Table 2: Composition of valve guide material suitable for methanol engine in Example 2

[0033] element C Cr Mo Ni Fe Content wt% 0.9 3.5 2.2 4.1 89.3

[0034] A preparation method for a valve guide material suitable for a methanol engine has the following process: ball milling mixing → pressing molding → high temperature sintering → vacuum oil impregnation → machining, specifically comprising the following steps:

[0035] (1) ball milling the raw material powders according to the proportion for 1.5 hours to mix them evenly, and the particle size of the raw materials after ball milling is ≤80 μm;

[0036] (2) Press the mixed powder into a mold on a press with a molding pressure of 28T;

[0037] (3) Sintering the formed blank in a sintering furnace at a high temperature of 1065°C for 1.5 h;

[0038] (4) Vacuum immersion oil treatment: vacuum degree 100Pa, immersion oil temperature 90℃, vacuum immersion oil time 45min;

[0039] (5) The finished product is machined using a carbide tool, wherein the tool speed is 1200 r / min, the tool feed is 60 mm / min, and the outer diameter of the finished product is 15.1 mm, the inner diameter is 8.45 mm, and the length is 80.3 mm.

[0040] Example 3

[0041] A valve guide material suitable for a methanol engine comprises components in the mass percentages shown in Table 3.

[0042] Table 3: Composition of valve guide material suitable for methanol engine in Example 3

[0043]

[0044]

[0045] A preparation method for a valve guide material suitable for a methanol engine has the following process: ball milling mixing → pressing molding → high temperature sintering → vacuum oil impregnation → machining, specifically comprising the following steps:

[0046] (1) ball milling the raw material powders according to the proportion for 2 hours to mix them evenly, and the particle size of the raw materials after ball milling is ≤80 μm;

[0047] (2) Press the mixed powder into a mold on a press with a molding pressure of 32T;

[0048] (3) Sintering the formed blank in a sintering furnace at a high temperature of 1070°C for 1.8 hours;

[0049] (4) Vacuum immersion oil treatment: vacuum degree 100Pa, immersion oil temperature 90℃, vacuum immersion oil time 45min;

[0050] (5) The finished product is machined using a carbide tool, wherein the tool speed is 1200 r / min, the tool feed is 60 mm / min, and the outer diameter of the finished product is 15.1 mm, the inner diameter is 8.45 mm, and the length is 80.3 mm.

[0051] The valve guide material suitable for methanol engine obtained in Examples 1-3 was subjected to abrasion resistance test, salt spray test and processability test, as follows:

[0052] 1. Wear resistance test (valve material: Ni30, test conditions: temperature 300°C, speed 1500rpm, test time 20 hours, wear tester), the specific results are shown in Table 4:

[0053] Table 4 Wear resistance test results

[0054] Valve guide material Valve guide wear mm Valve wear mm Total wear mm Standard material WR5520 0.029 0.010 0.039 Example 1 Materials 0.015 0.005 0.020 Example 2 Materials 0.010 0.003 0.013 Example 3 Materials 0.008 0.002 0.010

[0055] 2. Salt spray test (test conditions: add appropriate amount of HCOOH to 5% NaCl solution, adjust pH to 3.1-3.3 at room temperature, spray pressure 86KPa, 24 hours), the results are shown in Table 5:

[0056] Table 5 Salt spray test results

[0057]

[0058]

[0059] 3. Machinability test (test conditions: CBN tool, rotation speed 2000rpm, feed rate 0.1mm / r), the results are shown in Table 6:

[0060] Table 6 Processability test results

[0061] Valve guide material Tool life Standard material WR5520 2000 Example 1 Materials 1900 Example 2 Materials 1800 Example 3 Materials 1600

[0062] It can be seen from the test data in Tables 4-6 that the valve guide materials obtained in Examples 1-3 of the present invention use FeNiCrMo alloyed substrates prepared by ball milling, which effectively improves the corrosion resistance and wear resistance of the powder metallurgy seat rings, and can cope with harsh engine conditions, especially matching methanol engine conditions, but alloying slightly reduces the processing performance. As the alloy element content increases, the cost increases, the corrosion resistance and wear performance tend to be stable, but the machining performance decreases.

[0063] While controlling the cost of materials in Example 2, the corrosion and wear resistance of the valve guide are effectively improved, and the 500H methanol engine bench durability test is passed (engine durability test is an important means to evaluate the reliability and durability of the engine. The engine durability test is usually long and can last for hundreds or even thousands of hours. After the test, the engine will be disassembled and inspected to evaluate its wear degree and remaining life), meeting the methanol working conditions, and having good machining performance. The details are shown in the following table:

[0064] Table 7500H methanol engine bench durability test

[0065]

[0066]

[0067] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A valve guide material suitable for a methanol engine, characterized in that: The raw materials include the following elemental materials in percentage by mass: 0.6%-1.2% C, 0.5%-3.0% Mo, 1.0%-5.0% Cr, 2.0%-5.0% Ni, and the balance is Fe.

2. A method for preparing a valve guide material suitable for a methanol engine according to claim 1, characterized in that: The following steps are involved: (1) ball milling the raw material powders according to the proportion and mixing them uniformly; (2) Pressing the mixed powder into a shape on a press; (3) sintering the formed blank at high temperature in a sintering furnace; (4) subjecting the high-temperature sintered material to vacuum oil immersion treatment; (5) Machining the vacuum oil-impregnated material into a finished product.

3. The method for preparing a valve guide material suitable for a methanol engine according to claim 2, characterized in that: In the step (1), the ball milling is performed for 0.5-2 hours, and the particle size of the raw material after ball milling is ≤80 microns.

4. The method for preparing a valve guide material suitable for a methanol engine according to claim 2, characterized in that: In the step (2), the molding density is 6.7-7.0 g / cm 3 , the press tonnage is 25-35T.

5. The method for preparing a valve guide material suitable for a methanol engine according to claim 2, characterized in that: In the step (3), the sintering temperature is 1060-1100° C. and the sintering time is 1-2 hours.

6. The method for preparing a valve guide material suitable for a methanol engine according to claim 2, characterized in that: In the step (4), the vacuum degree of vacuum oil immersion is 100 Pa, the oil immersion temperature is 90° C., and the vacuum oil immersion time is 30-60 min.

7. The method for preparing a valve guide material suitable for a methanol engine according to claim 2, characterized in that: In the step (5), a carbide tool is used for machining, the tool speed is 800-1500 r / min, and the tool feed is 40-100 mm / min.

Images