JPH05306454A - Thermal spraying method for spacing adjustment - Google Patents

Abstract

PURPOSE:To enable uniform mixing and uniform supplying a resin and metallic powder. CONSTITUTION:This thermal spraying material is prepd. by mixing, by weight, 20 to 70% resin powder having >=180 deg.C heat resistance, 0.1 to 1.0% surfactant powder and the balance aluminum powder or pure aluminum powder. Since the surfactant powder is added at 0.1 to 1.0% to this material, the surfaces of the metallic powder particles and resin powder particles are enclosed by the ions of the ionic surface active material and the particles repulse each other and hardly flocculate. The particles are thus uniformly dispersed into the Al powder particles. The electrification to the resin is prevented by the sticking of the surfactant to the resin particles and since the surfactant acts as a lubricant, the flowability of the particles is greatly improved and the reproducibility of the film for spacing adjustment formed without deteriorating the erosion resistance is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spray for gap adjustment, which is formed in a portion of a compressor housing of an automobile turbocharger facing an impeller and is cut by an impeller as a mating member to adjust the gap. It is about materials.

[0002]

2. Description of the Related Art In a compressor housing of a turbocharger for an automobile, it is necessary to reduce a gap between a tip of an impeller and an inner wall surface of the compressor housing facing the impeller, that is, a gap of an air flow portion as small as possible. It is known to be advantageous in improving efficiency (compressor efficiency).

Therefore, an easy-to-cut thermal spray coating is formed in advance on the inner wall surface of the air flow part of the compressor housing so that the gap between the compressor housing and the impeller becomes substantially zero, and the impeller is mounted on the compressor housing. It is considered that the impeller is rotated by operating the actual machine, etc., and the sprayed coating is cut by the impeller that is the mating material to adjust the gap.

Among the conventional thermal spray materials for forming the thermal spray coating for adjusting the gap, one that may be used in the compressor housing of the turbocharger for automobiles is the operating temperature (120 to 18) of the compressor housing.
(0 ° C.) and the material of the impeller (aluminum alloy), the powder mixture of heat-resistant polyester plastic and Al shown in Japanese Patent Publication No. 52-4494 and Japanese Patent Publication No. 60-18746. Like Ni
-Graphite powder, and also Al-graphite powder.

Further, as a thermal spray material used to adjust the clearance of the compressor housing of a turbocharger for automobiles, foreign matter such as sand and pebbles often intrudes and collides with the compressor wall surface when the outside air is sucked in during actual vehicle operation. Erosion resistance is required for the thermal spray coating,
The companion material, the impeller, is a relatively soft aluminum alloy and has good machinability and less aggressiveness to the mating material, and the operating temperature of the compressor of the automobile turbocharger is about 180 ° C. Since it is necessary to take into consideration such factors as described above, JP-A-1-12062
In the invention of the thermal spray material for gap control disclosed in Japanese Patent Laid-Open Publication No. 5-50 wt%, resin powder of one or more kinds selected from polyphenylene sulfide, polyether sulfone and ethylene tetrafluoroethylene copolymer %, Balance Al
A thermal spray material for gap adjustment, which is characterized by comprising a mixed powder with an alloy powder, has been proposed.

[0006]

The thermal spray material for gap adjustment is often a composite material of a soft metal and a resin as described above, and in order to obtain a good reproducible thermal spray coating for gap adjustment, The important point is how each powder is uniformly mixed and stably supplied. As an example of this measure, for example, in the invention of Japanese Examined Patent Publication No. 52-4494, the shape of the resin is controlled (granulated).
In the invention of 0-18746, a special treatment such as coating graphite with Ni is indispensable instead of mixing, so that there is a demerit that the cost of the material becomes very high.

The situation is exactly the same when the invention of Japanese Patent Laid-Open No. 1-312062 is carried out. For example, unless special treatment such as granulation or coating is applied as described above, the degree of mixing of powders is When the mass production is considered, the stability (reproducibility) of the film for gap adjustment is ensured because the distribution amount of resin in the film changes due to unevenness and the film thickness formed changes due to changes in the powder supply amount. Very difficult to do.

Further, in the case of mixing the resin and the metal powder as in the case of the thermal spray material for adjusting the gap, the resin adsorbs moisture in the atmosphere at the time of mixing, or the resin becomes electrically charged and thus adheres to the Al particles. I can not mix well and well. Further, the specific gravity of Al particles and resin particles are remarkably different, which is one of the causes of non-uniformity.
Further, a phenomenon in which a metal sticks on the surface of a soft resin during mixing is observed, which further promotes nonuniformity.

The present invention has been made in view of the above-mentioned problem that the resin and the metal powder cannot be uniformly mixed in the thermal spray material for adjusting the gap, so that the distribution of the resin in the film formed is not uniform. Therefore, it is an object of the present invention to provide a thermal spray material for gap adjustment that can uniformly mix a resin and a metal powder.

[0010]

Means for Solving the Problems The inventors have paid attention to zinc stearate, which has been conventionally added as a lubricant in the field of powder metallurgy, and have been keen to use it to uniformly mix a resin and a metal powder. Repeated research. As a result, the inventors have newly found that zinc stearate acts not only as a lubricant but also as a surfactant to increase the fluidity of the mixed powder and prevent charging, and completed the present invention.

The thermal spray material for gap adjustment according to the present invention comprises a resin powder having a heat resistance of 180 ° C. or higher with a weight ratio of 20 to 70%,
The gist is that 0.1 to 1.0% of the surfactant powder is mixed with the balance of aluminum alloy powder or pure aluminum powder.

The resin powder used in the present invention is, for example, polyphenylene sulfide (P) because it has a working temperature of a compressor for an automobile turbocharger of less than 180 ° C. and has desired erosion resistance.
PS), polyether sulfone (PES), ethylene tetrafluoride ethylene copolymer (PETFE), polyether ether ketone (PEEK) and the like.

Further, as the surfactant, anionic type,
Any of cations may be used, but it is necessary that it is stable to heat (does not deteriorate), has a low melting point, and is easily sublimated by a plasma flame. Simply stearic acid is unstable to heat (altered at 60 to 70 ° C), and calcium stearate has a high melting point (about 800 ° C) and remains in the film when formed as a gap adjusting film. There is a possibility that it will end up.

As described above, when the particles of the surfactant remain in the film, the machinability is improved, but the bond between the particles is weakened, and thus the erosion is weakened. Therefore,
Zinc stearate (melting point 400 ° C.) is suitable as a substance that is easily sublimated by a plasma flame.

[0015]

Since 0.1 to 1.0% of the surfactant powder is added, the surfaces of the metal powder particles and the resin powder particles are surrounded by the ions of the ionic surfactant. for that reason,
The particles repel each other and are less likely to aggregate, and the resin particles are uniformly dispersed in the Al powder particles.

Further, the adhesion of the surfactant to the resin particles can prevent the resin from being charged. Further, Al fine powder has a risk of dust explosion, but the dust explosion resistance is also improved by preventing charging.

In addition, when zinc stearate is used, it also acts as a lubricant and significantly improves the fluidity of the powder. Moreover, when zinc stearate particles adhere to the surface of the resin particles, the phenomenon of metal sticking to the surface of the soft resin is prevented.

In the present invention, the amount of the surfactant added is set to 0.1 to 1.0% when it is less than 0.1%.
This is because the effect of adding a surfactant cannot be obtained sufficiently,
On the other hand, if it exceeds 1.0%, the surfactant remains in the formed gap adjusting film and impairs the erosion resistance.

The addition amount of the resin powder is set to 20 to 70% because the resin is sublimated by about 5% during thermal spraying and the amount is 15 to 65%.
%, But when the area ratio of the resin is less than 15%, the ratio of the impeller hitting Al increases, and the torque is increased due to the deterioration of the machinability, and the impeller wear increases. If it exceeds, the amount of resin will increase and the film will not be scraped even if the impeller hits it, just by compressing,
This is because the torque also increases and the adhesion strength with the material also decreases.

FIG. 3 is a diagram showing the relationship between the aflon area ratio of the thermal spray coating and the cutting torque when ethylene tetrafluoride ethylene copolymer (PETFE) (trade name: Aflon) is added. As is clear from FIG. 3, it is understood that a desired cutting torque can be obtained with an area ratio of AFLON of 15 to 65%.

[0021]

EXAMPLES Examples of the present invention will be described in comparison with a conventional example to clarify the effects of the present invention. As the sprayed powder for gap adjustment of the conventional example, pure Al (average particle size 30 μm) and 20 w
Evaluation was performed by mixing t% PETFE (average particle size 60 μm: trade name Aflon).

When Al and the resin were mixed as they were, as in the above-mentioned conventional example, the particles of Al and the resin adhered to each other, and it was impossible to mix them uniformly. In order to easily check this state, after mixing Al and resin in a mortar, they were filled in a graduated cylinder and tapped 50 times or more to measure the volume (density).
As a comparative example, the granulated powder was also mixed with Al and a resin, filled in a graduated cylinder, and tapped 50 times or more to measure the volume (density).

Next, as an example of the present invention, 0.1 to 1.0% of zinc stearate was further added to the Al and the resin powder, and the Al and the resin were mixed in the mortar in the same manner as described above, and then the graduated cylinder was placed. Fill and tap 50 times or more to get volume (density)
Was measured. The obtained results are summarized in FIG.

As shown in FIG. 1, in the conventional example, the Al particles and the resin particles were stuck together and could not be mixed well, so the density was the lowest at 1.02 g / cc. Further, although the granulated powder has improved fluidity, its density is 1.1 g / cc.
Met.

On the other hand, in the example of the present invention in which zinc stearate was mixed as the surfactant, the density was 1.19 to 1.
It was confirmed that the density was clearly increased to 22 g / cc. It was also found that the higher the amount of zinc stearate added, the faster the density reached.

FIG. 5 is a micrograph showing the state of particles of a mixed powder obtained by mixing Al and resin with 1.0% by weight of zinc stearate. In this way, it is possible to confirm that fine zinc stearate is attached to the surface of the resin.
From this, it is considered that the friction coefficient becomes small and the Al and the resin are well mixed with each other through the contact of the zinc stearate.

It has been confirmed that there is a certain correlation between the density measurement result and the mixing degree of Al and resin. That is, the degree of mixing is determined by sampling the powder and
It has been found that the higher the density, the more stable the mixing ratio can be obtained irrespective of the sampling location, as evaluated by EPMA elemental analysis of fluorine and fluorine.

Next, for the mixed powder obtained above,
Using an actual thermal spraying device (Metco, thermal spraying gun: 7BM, powder feeding device: 4MP), carrier flow: N ₂ gas 6 l / min, hopper pressure: 10 kgf / cm ² to stabilize the powder feeding. evaluated.

Under these conditions, the amount of fluctuation of the powder supply amount when continuously supplying for 1 hour was investigated, and the result is shown in FIG. As shown in FIG. 2, in the conventional example in which the surfactant was not mixed, the variation amount reached 15 g, and in the comparative example using the granulated powder, the variation amount was 7 g although the variation amount was improved. On the other hand, in the case of the present invention, it was found that the fluctuation amount was as small as 4 g due to the action of the surfactant, the fluidity was improved, and the resin powder could be uniformly mixed.

Next, as a thermal spray material of the present invention, pure Al is used.
(Average particle size 30 μm), Aflon (Average particle size 60 μm)
Using zinc stearate (average particle size 5 μm), the gap adjusting coating 12 was formed on the surface of the compressor housing 10 shown in FIG. 4 facing the impeller under the above-mentioned thermal spraying conditions by the above thermal spraying device.

The particle structure of the obtained gap adjusting film 12 is as shown in FIG. 6, and it was confirmed that the resin was evenly dispersed in the Al matrix, and the formed film thickness was changed. It was found that the reproducibility of the film thickness was excellent. Further, when the sprayed coating was subjected to an erosion test by shot blasting, it was confirmed to have sufficient erosion resistance.

In this embodiment, as the resin, PTET is used.
Only for F, PPS, PEEK and PE
It has been confirmed that similar results can be obtained for S as well.

[0033]

As described above in detail, the thermal spray material for adjusting the gap of the present invention has a heat resistance of 180- ° C resin powder of 20 to 70% by weight and a surface activity of 0.1 to 1.0% by weight. Agent powder, characterized in that the remainder is a mixture of aluminum alloy powder or pure aluminum powder,
Since 0.1 to 1.0% of the surfactant powder was added, the surfaces of the metal powder particles and the resin powder particles were surrounded by the ions of the ionic surface-active substance, so that the particles repel each other and were less likely to aggregate. The resin particles are uniformly dispersed in the powder particles. Further, by attaching the surfactant to the resin particles, it is possible to prevent the resin from being charged, and since the surfactant acts as a lubricant, the fluidity of the particles is remarkably improved and the erosion resistance is deteriorated. The reproducibility of the gap adjusting film which is formed without any trouble becomes excellent. Further, Al fine powder has a risk of dust explosion, but the dust explosion resistance can be improved by preventing charging.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the amount of zinc stearate added and the packing density of a thermal spray material for gap adjustment.

FIG. 2 is a diagram showing a fluctuation amount in a thermal spray powder supply test.

FIG. 3 is a diagram showing a relationship between a resin area ratio of a thermal spray coating and a work torque.

FIG. 4 is a sectional view of a compressor housing.

FIG. 5 is a micrograph showing the particle structure of the thermal spray material of the present invention.

FIG. 6 is a photomicrograph showing the metallographic structure of a spray coating for gap adjustment formed using the spray material of the present invention.

[Explanation of symbols]

10 Compressor housing 12 Spray coating for gap adjustment

Claims (1)

[Claims] 1. A heat resistance of 20 to 70% by weight of 180 ° C.
A thermal spray material for gap adjustment, comprising the resin powder as described above, 0.1 to 1.0% of a surfactant powder, and the balance being an aluminum alloy powder or pure aluminum powder.