JPH0543914A - Metal packed sintered alloy valve seat for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance and attackability against an object of a metal packed sintered alloy valve seat used as a structural member in internal combustion engines. CONSTITUTION:A valve seat for internal combustion engines is made of copper impregnated sintered alloy formed by impregnating with Cu or Cu alloy or lead impregnated sintered alloy formed by impregnating with Pb or Pb alloy a sintered alloy substrate having three phase mixed structure consisting of 3-15wt.% 1st phase of Fe-Cr-Co-W alloy having MHv 700-1800, 2-12wt.% 2nd phase of Co-Mo-Cr alloy having MHv 500-1000 and the balance 3rd phase of Fe-Co alloy having MHv 100-300, and 5-20wt.% porosity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat made of a metal-filled sintered alloy for an internal combustion engine, which shows excellent wear resistance even under severe conditions and has extremely low opponent attack.

[0002]

2. Description of the Related Art Conventionally, as a valve seat for an internal combustion engine of an automobile or the like, many other materials such as a copper infiltration sintered alloy described in JP-A-58-178073 are used.

[0003]

On the other hand, in recent years, the internal combustion engine has been remarkably increased in speed and output, and accordingly,
The operating environment of the valve seat, which is a structural member of this, is becoming more severe, but among the conventional valve seats, the one with excellent wear resistance has a large opponent attack, while the one with a low opponent attack At present, it is inferior in wear resistance and does not have both of these characteristics, and therefore does not exhibit sufficient performance for practical use under severe conditions.

[0004]

Therefore, the present inventors have
From the above viewpoints, as a result of research to develop a valve seat for an internal combustion engine that exhibits excellent wear resistance in a harsh environment of use and has low opponent attack, the valve seat is Hereinafter,% relating to the composition ratio represents weight%), and the micro Vickers hardness (MHv) is 700 to 1
Fe-Cr-Co-W alloy phase having 800 (hereinafter referred to as the first phase): 3 to 15%, MHv: 500 to 1000
-Mo-Cr-based alloy phase (hereinafter referred to as the second phase) having 2 to 12% and F having MHv: 100 to 300
e-Co alloy phase (hereinafter referred to as the third phase): Cu or Cu alloy is infiltrated into a sintered alloy substrate having a three-phase mixed structure of the following ratio and a porosity of 5 to 20%. Or a Pb or Pb alloy impregnated copper infiltration sintered alloy or lead impregnated sintered alloy,
The result of this study is that the resulting metal-filled sintered alloy valve seat exhibits excellent wear resistance even in practical use under severe conditions, and the wear of the valve, which is a mating member, is extremely small.

The present invention has been made based on the above research results, and the first phase of the Fe-Cr-Co-W alloy having MHv: 700 to 1800: 3 to 15
%, MHv: Co-Mo-C with 500-1000
Second phase of r-based alloy: 2 to 12%, MHv: 100 to 30
Cu or a Cu alloy is infiltrated into a sintered alloy substrate having a three-phase mixed structure having a ratio of the third phase of the Fe-Co alloy having 0: the rest, and a porosity of 5 to 20%. And a lead-impregnated sintered alloy impregnated with Pb or a Pb alloy.

In the valve seat of the present invention,
Fe-Cr-C of the first phase of the sintered alloy substrate constituting this
The o-W alloys are: Co: 10 to 30%, W: 5 to 30%, Cr: 20 to 40%, Nb: 0.2 to 2%, Si: 0.2 to 2%, C: 1 to 1. 3%, with the balance being Fe and inevitable impurities, the second phase of the Co-Mo-Cr alloy is Mo: 20-40%, Cr: 5-15%, Si: 1 to 5%, with the balance being Co and unavoidable impurities, and a third phase Fe-Co alloy is: Co: 2 to 10%, Mo: 0.5 to 3%, Ni : 0.5 to 4%, C: 0.5 to 1.5%, and, if necessary, Cr: 0.5 to 5%, Nb: 0.1 to 2%, It is desirable to contain one type or two types, and the composition of the balance of Fe and inevitable impurities, respectively.

In the valve seat of the present invention,
The hardness and the content ratios of the first to third phases constituting the sintered alloy substrate are all empirically determined based on a large number of test results, and therefore, the hardness and the content of each phase. If any of the above goes out of the range,
The overall hardness balance of the valve seat may be lost, and the hardness may be relatively lowered or increased, and the desired wear resistance may not be obtained or the opponent's aggression may be increased. Therefore, by limiting the hardness and the content ratio of the first to third phases within the above ranges, desired excellent wear resistance and small opponent attacking property are ensured.

Further, the hardness of each of the first to third phases can be obtained by limiting the alloy composition constituting the same as described above, and the control of the hardness within the above range is determined by the alloy composition. By adjusting the.

On the other hand, if the porosity is less than 5%, copper infiltration or lead impregnation is insufficient and desired strength cannot be obtained. On the other hand, if the porosity exceeds 20%, wear resistance becomes poor. The porosity was set to 5 to 20% because the porosity was significantly reduced. Further, as the copper infiltration material, oxygen-free copper, C
Cu-1 having a composition of u-1 to 4% Co-1 to 2% Zn
Co-Zn alloy, and Cu-2-5% Fe-1-6%
Cu-Fe-Mn- having a composition of Mn-1 to 4% Zn
It is desirable to use a Zn alloy, and the lead impregnation material is pure P
b, Pb-30 to 40% Sn alloy is preferably used.

[0010]

EXAMPLES Next, the valve seat of the present invention will be described in detail with reference to Examples. As raw material powders, Table 1 and Table 2,
And a particle size having the hardness and composition shown in Table 3: 1
Atomized powder of 00 mesh or less was prepared, these raw material powders were blended in the blending composition shown in Tables 4 and 5, and zinc stearate: 1% was added and mixed for 30 minutes in a mixer, then 5 to 7 ton / cm 2. ^The green compact is press-molded at a predetermined pressure within the range of ² , and the green compact is held at 500 ° C. for 30 minutes to degrease, and then in an ammonia decomposing gas atmosphere, 1
Sintering under a condition of holding at a predetermined temperature within a range of 100 to 1200 ° C. for 1 hour gives a composition having the same porosity as shown in Tables 4 and 5 and having substantially the same composition as the composition. Sintered alloy substrates having a three-phase mixed structure are formed, and pure Cu consisting of oxygen-free copper, Cu-2.4% Co-1. 3% Zn alloy (hereinafter referred to as Cu alloy 1) or Cu-3.6%
Fe-4.1% Mn-2.1% Zn alloy (hereinafter referred to as Cu alloy 2) was placed in the combination shown in Tables 4 and 5, and was melted with copper under the condition of keeping the temperature at 1100 ° C. for 15 minutes. To form a copper infiltrated sintered alloy.
Heat treatment is performed under a condition of holding at a predetermined temperature within a range of 00 to 700 ° C. for 1.5 hours, and the remaining sintered alloy substrate is
Pure Pb or Pb-35% heated to 600 ° C in a nitrogen atmosphere with a pressure of 8 kg / cm ² applied to the bath surface
By impregnating lead in a bath of Sn alloy for 1 hour under a condition of immersion to obtain a lead-impregnated sintered alloy, both have an outer diameter of 3
Metal-filled valve seats 1 to 16 of the present invention and comparative metal-filled sintered alloy valve seats 1 to 12 having dimensions of 4 mm x inner diameter: 27 mm x thickness: 7 mm were manufactured.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

In the comparative metal-filled sintered alloy valve seats 1 to 12, any one of the hardness and content ratio of the first to third phases and the porosity in the sintered alloy base material constituting the valve seats is used. This is outside the scope of this invention.

Next, regarding the various metal-filled valve seats obtained as a result, the material of the valve: JIS SUH36, the heating temperature of the valve: 850 to 900 ° C., the seating number of the valve: 3000 r. p. m. Atmosphere: Propane gas with a pressure of 0.4 kg / cm ² and combustion gas with oxygen at a flow rate of 1.6 l / min, Surface heating temperature of valve seat (internal water cooling): 350-4
A wear test was performed under the conditions of 00 ° C. test time: 100 hours, and the maximum wear depth of the valve seat and the maximum wear depth of the valve, which is a mating member, were measured. The measurement results are shown in Tables 4 and 5.

[0018]

From the results shown in Tables 4 and 5, all of the metal-filled valve seats 1 to 16 of the present invention have excellent wear resistance and low opponent attacking property, while the comparative metal As seen in the filled valve seat, the hardness and content of the first to third phases constituting the sintered alloy substrate,
Also, if any of the porosities deviates from the scope of the present invention, it is clear that at least one of wear resistance and opponent attacking property becomes poor.

As described above, the valve seat made of the metal-filled sintered alloy of the present invention has excellent wear resistance and remarkably small opponent attack property, and therefore exhibits excellent performance even during practical use under severe conditions for a long time. It will be exerted over a period of time.

Claims (2)

[Claims] 1. Micro Vickers hardness (MHv): 7
First phase of Fe-Cr-Co-W based alloy having 00 to 1800: 3 to 15%, MHv: Second phase of Co-Mo-Cr based alloy having 500 to 1000: 2 to 12%, MHv: A sintered alloy substrate having a three-phase mixed structure of a ratio (above wt%) consisting of a third phase of the Fe-Co alloy having 100 to 300: the rest, and a porosity of 5 to 20%,
A valve seat made of a metal-filled sintered alloy for an internal combustion engine, which is composed of a copper-infiltrated sintered alloy formed by infiltrating Cu or a Cu alloy. 2. Micro Vickers hardness (MHv): 7
First phase of Fe-Cr-Co-W based alloy having 00 to 1800: 3 to 15%, MHv: Second phase of Co-Mo-Cr based alloy having 500 to 1000: 2 to 12%, MHv: A sintered alloy substrate having a three-phase mixed structure of a ratio (above wt%) consisting of a third phase of the Fe-Co alloy having 100 to 300: the rest, and a porosity of 5 to 20%,
A valve seat made of a metal-filled bond gold for an internal combustion engine, which is made of a lead-impregnated sintered alloy impregnated with Pb or a Pb alloy.