JPS5949306B2 - Fine composite powder for forming wear-resistant thermal spray layers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides, for example, piston rings, rocker arms,
The present invention relates to a fine composite powder suitable for use in forming a wear-resistant sprayed layer on the sliding surfaces of shift forks, valves, valve seats, etc.

Conventionally, for compression piston rings such as those used in high-load gasoline engines and diesel engines, the sliding surface of the cast iron piston ring body has been coated with
Cr plating or Mo sprayed layer is applied, but piston rings with Cr plating originally have low oil retention properties, so they tend to scuff between them and the liner, which is the mating member. The latter piston ring with a Mo sprayed layer has good oil retention, but the Mo sprayed layer has poor adhesion to the piston ring body, so the Mo sprayed layer peels off and the piston rings are damaged. This had problems such as the ring itself being worn out. Conventionally, when spraying carbide particles such as W carbide and Mo carbide, or hard particles such as Fe-Cr and Fe-Mo,
In order to improve the adhesion with the base material and the carbide particles or hard particles, Ni, Mo, Ni-M alloy, or
The use of metal particles, such as 3% Cr stainless steel, as a binder has been practiced, but since the metal binder is soft, it ensures the desired excellent wear resistance of the sprayed layer formed. However, there were other problems such as the thermal spraying process being complicated. From the above-mentioned viewpoints, the present inventors developed a powder for forming a thermal spray layer in order to form a thermal spray layer that has good adhesion to the base material, excellent wear resistance, and excellent oil retention performance. As a result of research,
As raw material powder, Vickers hardness: 600 to 1
Fe-Cr powder with 300, Fe-Mo powder tag F'e
- one or more ferroalloy powders selected from W powder, Fe-Nb powder, and Fe-V powder, iron oxide powder, carbon powder, Cr oxide powder, MO oxide powder, and W oxide powder; Use either or both of the powders,
These raw material powders are blended to have a predetermined final component composition, pulverized and mixed to an average particle size of 10 μm or less, and the resulting mixed powder is treated by a co-reduction method in which heat reduction is performed in vacuum or in a reducing atmosphere. Then, it becomes a hard dispersed phase in the sprayed layer, and both have a Vickers hardness of 600 to 130.
Fe-Cr having an average particle diameter of 10 μm or less, . Fe
-MO. Fe-W,. Hard particles of one or more of Fe-Nbl} and Fe-V, and Cr-Cr carbide particles and MO-MO carbide, both of which have an average particle size of 10 μm or less, and which serve as a binder phase in the sprayed layer. particle,
A fine composite powder in which W-W carbide particles and Fe particles are weakly bonded to each other is obtained.
When a composite powder containing seeds, Fe and unavoidable impurities: the remainder is used for forming a thermal spray layer, this composite powder is so fine that it has poor penetration. It is possible to form a sprayed layer with excellent adhesion to the base material, and the formed sprayed layer has an average particle size of 4.
Thermal spray particles of 0 to 70 μm are piled up and layered, and the thermal spray particles have a structure in which hard particles with an average particle size of 10 μm or less are uniformly dispersed, resulting in excellent wear resistance. Fine pores are dispersed in the sprayed layer, resulting in excellent oil retention performance.Furthermore, the above-mentioned composite powder has 5 particles that are weakly bonded to each other, so it can be used for any desired purpose. Since the particle size can be adjusted, the thermal spraying conditions can be kept constant, resulting in stable material quality and a well-finished thermal sprayed layer.

This invention was made based on the above knowledge, and the average particle diameter of each particle constituting the composite powder is shown below. The reason why the hardness of the hard particles and the component composition are limited as described above will be explained. (a) Average particle size of each particle If the average particle size exceeds 10 μm, penetration will deteriorate and the adhesion of the sprayed layer to the matrix will deteriorate, and the composite powder can be adjusted to an arbitrary particle size. Therefore, the average particle size of each particle was determined to be 10 μm or less.

(b) If the hardness of the hard particles is less than 600 on the Bitkers scale, the desired excellent wear resistance cannot be secured;
If the hardness exceeds 001, the compatibility with the mating material deteriorates, so the hardness was determined to be 600 to 1300 in terms of Vickers hardness.

(c) Ingredient Composition 1 Hard Particles If the content is less than 10%, it will not be possible to impart the desired wear resistance to the sprayed layer, and for example, when applied to the sliding surface of a piston ring, it will On the other hand, if the content exceeds 70%, the relative amount of hard particles becomes too large, causing damage to the thermal spray layer from the base material. Since the adhesion deteriorates, the content was set at 10 to 70%.

Note that the content is preferably 30 to 50%. 2C C has Cr. MQ. When the content is less than 1%, the desired effect cannot be obtained; If the content exceeds 1%, free carbon will precipitate and the wear resistance will deteriorate, so the content was set at 1% to 6%.

}, within the scope of this invention, on the side where the C content is low, the Cr. M.O. $? and W (metallic state) increases, and the amount of carbides of these metals increases on the high side.

3Cr If the content is less than 5%, the desired wear resistance cannot be ensured in the binder phase of the sprayed layer, while if the content exceeds 30%, embrittlement becomes significant. Its content was set at 5-30%.

Similar to Cr, MO and W have the effect of forming carbides and improving the wear resistance of the binder phase in the sprayed layer, but their content is higher than MO:2. Less than %, W: 2%
If it is less than MO, the desired effect cannot be obtained;
Containing W in excess of 1001) does not produce any further improvement, and the adhesion of the sprayed layer to the base material deteriorates, and W in excess of 6% causes the opposite material to deteriorate. Not only will it become damaged, but it will also damage the sprayed layer.
Since the interparticle bond between particles also decreases, MO:
2 to 10% and W: 2 to 6%, respectively.

Next, this invention will be explained by way of examples.

As a raw material powder, Fe-Cr powder (Cr: 62% by weight) having an average particle size of 65 μMf and having a Vickers hardness of 1050 was used.
), average particle size 6 with Bitkers hardness: 1100
5μMf) Fe-MO powder (MO: 70% by weight content),
Average particle size 65μMf with Vickers hardness: 1100
) Fe-W powder (containing W: 81% by weight), average particle size 65 μMf with Vickers hardness: 1000) F'e-N
b powder (containing Nb: 65% by weight), Bitkers hardness: 1
Fe-V powder (V
:52% by weight), iron oxide powder with an average particle size of 10 μm,
Carbon powder of 0.5 μm, 10 μM of MOcr oxide powder, 10 μM of MO-V powder, 10 μm of w
Oxide powders were prepared, these raw material powders were blended to have the final component composition shown in Table 1, and these blended powders were wet-pulverized and mixed in a ball mill for 10 hours to obtain particles with a particle size of 0. After forming mixed powders with a diameter of 1 to 5 μm, each of these mixed powders was heated in hydrogen at a temperature of 100°C.
Heat to 0°C and hold for 3 hours to perform heat reduction treatment,
Composite powders 1 to 23 of the present invention and comparative composite powders 1 to 3, each having the final component composition shown in Table 1, were manufactured.

Both Comparative Composite Powders 1 and 2 do not contain hard particles, and Comparative Composite Powder 3 has a content of hard particles that is higher than the range of the present invention.

Further, in the composite powders 1 to 23 of the present invention, the individual particles constituting each had a particle size of 0.5 to 5 μm or less and were weakly bonded to each other.

Then, using a normal thermal spraying machine, the outer diameter was 91mm. A thermal spray layer was formed on the sliding surface of a φ cast iron piston ring with the liner using the above-mentioned composite powders 1 to 23 of the present invention and comparative composite powders 1 to e, respectively. The piston rings 1 to 23 of the present invention and the comparative piston rings 1 to 3, each having a WOT/4000r. p. 110. A 20-hour operating test was conducted using an actual machine under the following conditions, and the amount of change in the piston ring gap between before and after the test, as well as the amount of peeling in the thermal sprayed layer when the piston ring was stretched at both ends to widen the gap, was measured. Alternatively, the length of the separation gap at the time when cracking occurred was measured.

The abrasion resistance was evaluated based on the amount of change in the gap, and the adhesion of the sprayed layer was evaluated based on the length of the separation gap. Therefore, the smaller the amount of change in the gap, the better the wear resistance, and the longer the length of the separation gap, the better the adhesion of the sprayed layer. It is assumed that the piston ring 23 of the present invention was subjected to heat treatment at a temperature of 400° C. for 1 hour after thermal spraying. The measurement results are shown in Table 2.

Table 2 also shows a Cr-plated piston ring (referred to as conventional piston ring 1) for the purpose of comparison.
Also shown are test results conducted under the same conditions on a piston ring with a MO sprayed layer (referred to as conventional piston ring 2).

Furthermore, the hardness (Vickers hardness) of the sprayed layer of each of the above-mentioned piston rings is also shown. As is clear from the results shown in Table 2, the conventional piston rings 1 and 2 with Cr plating and MO thermal spraying have excellent wear resistance and thermal spray coating, despite the extremely high hardness of the sliding surfaces. Comparative piston rings 1 and 2, which have thermally sprayed layers that do not have good layer adhesion and do not contain hard particles, are soft, but have superior wear resistance than the conventional piston rings 1 and 2, and also have a thermally sprayed layer that does not contain hard particles. Adhesion has become excellent.

On the other hand, piston rings 1 to 23 of the present invention, each having a sprayed layer in which hard particles with an average particle size of 10 pm or less exist as a hard dispersed phase, are all compared to conventional piston rings 1 and 2 and comparative piston rings 1 and 2. As a result, it exhibits even better wear resistance, and the adhesion of the sprayed layer is also excellent. Furthermore, the piston ring 23 of the present invention has been heat-treated to increase its hardness, exhibit excellent wear resistance, and have excellent adhesion. In Comparative Piston Ring 3, the sprayed layer contained hard particles in a content higher than the range of the present invention, so although it exhibited excellent wear resistance, the adhesion of the sprayed layer was extremely poor. There is one in As mentioned above, the composite powder of the present invention has excellent adhesion to the matrix and wear resistance, and can form a thermal sprayed layer with a clean finished surface through a simple thermal spraying process, making it industrially useful. It brings about an effect.

Claims (1)

[Claims] 1. Average particle size of 10 μm, all of which have a Vickers hardness of 600 to 1300 and become a hard dispersed phase in the sprayed layer.
The following Fe-Cr, Fe-Mo, Fe-W, Fe-Nb
, and one or more types of hard particles of Fe-V, and Cr-Cr carbide particles, both of which also have an average particle size of 10 μm or less, which serve as a binder phase in the sprayed layer, M
Composed of o-Mo carbide particles, W-w carbide particles, and Fe particles, and in weight%, hard particles: 10~
70%, C: 5 to 30%, and further contains any one or two of the following: Mo: 2 to 10%, W: 2 to 6%, Fe and inevitable impurities: the remainder A fine composite powder for forming a wear-resistant thermal spray layer, characterized by having a composition consisting of.