JPS6164856A - Icon compound sintered alloy for valve seat - Google Patents

Abstract

PURPOSE:To develop an Fe sintered alloy for valve seat which is excellent in heat resisting property, corrosion resistance and wear resistance by mixing such powder as C, Co, Fe-Mo, etc. by a specified percentage in a powder of an Fe alloy of a specified composition, and forming and sintering them. CONSTITUTION:In an Fe base alloy powder containing 1-20wt% one kind or two kinds or more among Cr, Mo, V and Mn, 0.3-2.0wt% carbon powder, 3-15wt% Co powder, 3-15wt% Fe-Mo powder whose Mo content is 60-70%, 5-40wt% one kind or two kinds or more among Cr, Mo, W, V, Co and Si containing a carbide whose hardness Hv is 800-1,800 for crystallizing or depositing one kind or two kinds or more of elements selected from among Cr, Mo, W and V after sintering, and 3-60wt% one kind of two kinds or more of a hard Fe alloy which contains 0.5-2wt% C and whose hardness Hv after sintering becomes 300-900 are mixed, formed and sintered, and 1-20wt% Pb is infiltrated as necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ferrous sintered alloy for valve seats used in internal combustion engines.

[Conventional technology]

Various materials have been proposed for valve seats for internal combustion engines, particularly for valve seats for internal combustion engines for automobiles, in order to prevent pulse reset due to lead-free gasoline fuel. Examples include iron-based sintered alloys containing PeMo, Co, and 0 and having good wear resistance.

[Problems to be solved by the invention] However, in recent years, demands for higher performance in internal combustion engines have led to stricter demands on valve seats, and further improvements in heat resistance, corrosion resistance, wear resistance, etc. are desired. . In order to meet these demands, it is conceivable to use a large amount of expensive materials, but this will result in high costs.

An object of the present invention is to provide an iron-based sintered alloy for valve seats that has excellent heat resistance, corrosion resistance, wear resistance, etc.

[Means for solving problems]

The iron-based sintered alloy for valve seats of the present invention has a) Or
The base material is one or more iron-based alloys containing 1 to 20 weight parts of one or more elements selected from the group consisting of Mo, V, and Mn, and in total weight ratio, b) a13~ 2ch, c) Co'5-15%.

a) FeMo3 containing 60-70% MO by weight
~15ch.

and e) Hardness that crystallizes or precipitates one or more elements selected from the group consisting of Or1Mo, W and V after sintering) iv
Or%Mo1W containing 800-1800 carbides,
5 to 40 of 11 or 2 or more of V, Co and Si
FeMo and a hard iron-based alloy containing one or two or more hard iron-based alloys containing 15 to 2 ZS of FeMo and C, and having a hardness of sintered maple of Hv 300 to 900. is uniformly dispersed in the sintered alloy base.

In the following description of the present invention, unless otherwise specified, "weight%" is indicated.

In the present invention, an iron-based alloy containing 6-18% of Or as a matrix, an iron-based alloy containing 1-5% of Cr, 1-1tlJ of MocL and 1-1% of Vα, and/or an iron-based alloy containing 1-18% of Or (
15-2%, MoCLl~1chi and Mu [
Preferably, iron-based alloys containing 11-1% are used.

In addition, as hard iron-based alloys, MoQ, 5-6chi, Or6
~18%, VCL1~1%, SiQ, 1~1% and 0 (
Iron-based alloy containing L5-2, Mo 1-10, O
r 1~10chi, Vo, 5~61p, Si (Ll ~
Iron-based alloy containing 1%, W1-10% and CcL5-2- and/or MoQ, 5-6, Or 15-6
%, V C15~6%, 3i111~1%, W5~
It is preferable to use an iron-based alloy containing 5 to 154-154N and 5 to 2 CrL.

If necessary, 1 to 20% of Pb may be added to the iron-based sintered alloy.
It is preferable to infiltrate.

The reason for limiting each component element used in the present invention will be explained below.

First, to explain the iron-based alloy for base material of the present invention, Or
By using 1fi or two or more of iron-based alloys containing 1 to 20% of one or more elements selected from the group consisting of , Mo, V, and Mn, the heat resistance and corrosion resistance of the iron base can be improved. Or, Mo, V and Mn
If the addition of one or more elements selected from the following is less than 1, the effect will be small; on the other hand, if the addition exceeds 20, the effect will not be improved.

C (carbon) dissolves and diffuses into the iron base during sintering to promote sintering and strengthen the iron base, and this effect is not seen when C is added in an amount less than α3. If C is added in excess of 2, the amount of C remaining in the matrix as free graphite becomes too large and the strength of the matrix decreases, so it was limited to α3 to 2.

Co (cobalt) dissolves into the iron base during sintering and strengthens it, improving heat resistance and maintaining high-temperature strength, but this effect is not seen when less than 5% Co is added. ,
On the other hand, even if -Co is added in excess of 15%, no further effect can be obtained, and the inverted-coat base material becomes soft and wear increases.
Furthermore, since Co is expensive and it is economically disadvantageous to add a large amount of Oo, it is limited to 3 to 151.

FeMo (ferromolybdenum) has Mo of 60 to 70
Vickers hardness 1 (v6DO~130)
It has a hardness of 0. Fine hard particles of FeMo are dispersed in the base material and exhibits wear resistance due to the paving stone effect. If the amount of FeMo added is less than 3 mm, the wear resistant component is too small. On the other hand, if FeMo is added in excess of 15 inches, the wear-resistant components will be too large, damaging the mating component and making cutting difficult. Limited.

Hard iron-based alloys exhibit wear resistance due to carbides that are partially dispersed in the base material to strengthen the base material and increase heat resistance. If the amount is less than 3%, the above effects will be small, while if it is added in excess of 60 inches, cutting becomes difficult, so the range was limited to 5 to 60 inches.

Pb infiltration is performed under more severe usage conditions, and Pb
Interposed in the contact area between the trS valve and the valve seat, pb
By forming an oxide layer, it acts as a lubricant and improves the mutual wear resistance of the valve and valve seat.If the Pb infiltration is less than 1-, the effect of the Pb infiltration will not appear.
Pb infiltration exceeding 20 inches weakens the skeleton of the sintered body and increases wear, so it was limited to 1 to 20 inches.

The compacting pressure when compacting the mixed powder for producing a sintered body is preferably 6 to 7 t/-.

In addition, the molded body is sintered in a reducing atmosphere with a concentration of 1,100 to 1
, 250'O with an I trowel for 30 to 60 minutes. When infiltrating Pb, the sintered body is brought into contact with Pb, and the sintered body is again infiltrated with Pb in a reducing atmosphere.
It is advisable to heat the product for 30 to 60 minutes using a trowel at a temperature of 0 °C.

[Effect]

The present invention is based on one or more iron-based alloys containing 1 to 20 elements selected from the group consisting of Or, Mo, V, and Mn. FeMo 3 to 1, which improves heat resistance and corrosion resistance, adds 3 to 2 inches of carbon, strengthens the substrate, and adds 5 to 15 degrees of carbon, is effective in maintaining heat resistance, and contains 60 to 70 of Mo.
Addition of 5% improves wear resistance, and addition of 1ai or 2 or more types of hard particles made of iron-based alloys other than FeMo to 3~
20- Addition acts to improve heat resistance, corrosion resistance, and wear resistance. Also, if necessary, add 1 to 20 pb.
Infiltration can improve wear resistance and lubricity.

〔Example〕

The present invention will be explained below with reference to Examples.

Example Table 11 Alloy powder for substrate shown (-100 mesh), F
eMo powder (-200 mesh), Co powder (-100
Mesh), C powder (-525 mesh), and hard iron-based alloy powder (-100 mesh) shown in Table 2 were blended according to the composition shown in Table 3, and zinc stearate was further added to α5-1-
The mixture is added, mixed, and molded at a molding pressure of 7 t/cd to produce a molded body. Next, this compact was sintered for 45 minutes at a temperature of 1.150'O in an ammonia decomposition gas atmosphere.

In addition, for sample numbers 10 and 20, the obtained sintered body was heated again at 1,050 ml with Pb lumps in an ammonia decomposition gas atmosphere.
Infiltration of pb was performed by heating with SO at a temperature of °C for minutes.

A valve seat described in Japanese Unexamined Patent Publication No. 48-90907 was used as a comparison material.

The wear amount, radial crushing strength, overall hardness, and hard particle hardness of each of these materials were measured, and the results are shown in Table 4. To measure the amount of wear, as shown in Fig. 1, a test piece 1 is pressed against a rotor 2 made of 8450 quenched and tempered material with a spring 3, and the rotor 2 is rotated at a sliding speed r: L5 bath/8 e C.
The test was conducted under the conditions of a friction distance of 100 mm and a final load of 2-1 Kf, and the wear width 4 of the test piece 1 was defined as the amount of wear, as shown in FIG.

Table 1 Composition table of iron-based alloy powder for substrate 3 Example composition table 3 (continued) Example composition table 4 Example result table 4 (continued) Example result As can be seen from the results shown in Table 4, b was melted. The wear amount of the unsoaked invention material is 1.32 to 1.49■, and P
1.77 and lo of the wear amount of the comparative material not infiltrated with b
The amount of wear of the comparative material infiltrated with Pb is less than that of om.
It showed a wear amount equivalent to or close to that of 55 mm, and excellent wear resistance equivalent to or close to that of a conventional Pb infiltrated product without Pb infiltration. Furthermore, the wear amount of the invention material infiltrated with Pb was 1.16 and 126 m, showing even more excellent wear resistance.

The radial crushing strength of the invented materials was 39 to 58, except for sample number 10.
k, g f/horse mackerel * (6oo'c) 50kgf/m of sample number 21 comparison material! (600'0).

The invented material of sample number 10 has a radial crushing strength of 80 kgf/aw!
(at 600°C), it was considerably superior to the comparative material.

〔Effect of the invention〕

The present invention makes it possible to obtain an iron-based sintered alloy for valve seats that has excellent heat resistance, corrosion resistance, and wear resistance by having the composition as described above.

The iron-based sintered alloy of the present invention exhibits excellent wear resistance without infiltration of PB, which is almost equivalent to that of conventional PB infiltration, and as a result, there is a problem of environmental pollution caused by PB from the valve seat. will not occur. Furthermore, if necessary, the obtained sintered body is coated with l? By infiltrating b, it is possible to obtain an iron-based sintered alloy for valve seats having even better wear resistance.

Furthermore, depending on the component composition, it is possible to obtain not only a valve seat with a radial crushing strength comparable to that of conventional valve seats, but also a valve seat with a radial crushing strength superior to that of conventional valve seats.

Furthermore, excellent wear resistance can be obtained without using large quantities of expensive materials such as Co and Mo.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a wear test conducted in an example of the present invention, and FIG. 2 is a diagram showing the amount of wear of the test piece shown in FIG. 1. In the figure, 1... Test piece, 2... A-ta, 3... Pressing spring, 4... Wear width tooth 1 Figure 111. Test piece 2...Rotor 3...1

Claims (2)

[Claims] (1)a) The base material is one or more iron-based alloys containing 1 to 20% by weight of one or more elements selected from the group consisting of Cr, Mo, V, and Mn, and the total weight b) 0.3-2% of C, c) 3-15% of Co, d) FeMo3-15 containing 60-70% by weight of Mo.
%, and e) Cr, Mo, W, containing a carbide with a hardness of Hv 800 to 1800 that crystallizes or precipitates one or more elements selected from the group consisting of Cr, Mo, W and V after sintering. A hard iron-based alloy containing 5 to 40% by weight of one or more of V, Co and Si and 0.5 to 2% by weight of C, and having a hardness of Hv 300 to 900 after sintering. An iron-based sintered alloy for a valve seat, comprising 3 to 60% of one or more of two or more kinds, and characterized in that FeMo and a hard iron-based alloy are uniformly dispersed in a sintered alloy base. (2)a) The base material is one or more iron-based alloys containing 1 to 20% by weight of one or more elements selected from the group consisting of Cr, Mo, V, and Mn, and the total weight b) 0.3-2% of C, c) 3-15% of Co, d) FeMo3-15 containing 60-70% by weight of Mo.
%, and e) Cr, Mo, W, containing a carbide with a hardness of Hv 800 to 1800 that crystallizes or precipitates one or more elements selected from the group consisting of Cr, Mo, W and V after sintering. A hard iron-based alloy containing 5 to 40% by weight of one or more of V, Co and Si and 0.5 to 2% by weight of C, and having a hardness of Hv 300 to 900 after sintering. 1 to 20% by weight of Pb is infiltrated into a sintered alloy in which FeMo and a hard iron alloy are uniformly dispersed in the sintered alloy base, consisting of 3 to 60% of one or more of the following. A ferrous sintered alloy for valve seats featuring: