JPH0266151A - Composite thermal spray material and its manufacturing method - Google Patents

Abstract

PURPOSE:To produce the compounded thermally spraying material which is uniform and amorphous and forms a film having excellent wear resistance, corrosion resistance, etc., by spray drying a slurry contg. alumina sol, silica sol and zirconium compd., then calcining the slurry. CONSTITUTION:Water or org. solvent such as alcohol is mixed with the soln. of the alumina sol, silica sol and zirconium compd. such as ZrCl4 or a mixture of a prescribed compsn. composed of zirconium oxide sol to prepare the slurry. This slurry is spray dried by about 70 to 500 deg.C hot air. The resultant spray dried material is calcined at about 250 to 600 deg.C in an oxidative atmosphere to remove the anions, etc., contained therein. The compounded thermally spraying material contained therein. The compounded thermally spraying material consisting of 45 to 70wt.% Al2O3, 1 to 50% SiO2, and 5 to 50% ZrOx (0<x<=2) is obtd. in this way. This thermally spraying material is the amorphous material uniformly compounded with the components and is easily meltable to form the film having the excellent characteristics such as wear resistance and corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composite thermal spray material and a method for producing the same, and more specifically to a composite thermal spray material containing alumina, silica, and zirconium oxide in specific proportions, and the composite thermal spray material. An efficient method for producing thermal spray materials.

[Prior art and problems to be solved by the invention] In general, thermal spraying involves melting metal or ceramics and spraying it onto the object to be thermally sprayed using the force of compressed air or compressed inert gas. This is a method of forming a ceramic coating. Therefore, when ceramics or the like is used as a thermal spraying material, it has high hardness, high wear resistance, high heat resistance, high strength,
It can form an excellent coating with high corrosion resistance and can be used as a structural material.

However, since ceramics have a high melting point, the powder is difficult to melt, resulting in a large number of pores and easy mixing of unmelted substances, which often results in lower corrosion resistance. Furthermore, since the coefficient of thermal expansion is lower than that of ordinary metals, the actual situation is that the metal substrate and the ceramic coating often break due to thermal stress.

To date, several ceramic-based thermal spray materials have been developed. For example, in Japanese Patent Publication No. 62-41310, basic oxides (especially A
ftoy, MgO, Cab.

B a O, Cr z O3, T i O2, Z r
(Oz) and 1 to 50% by weight of a glass-forming oxide, such as SiO For example, it is described that the agglomerate is passed through a membrane of water or air, and the resulting agglomerates are recovered and powdered for use as a thermal spray material. The coating formed by spraying this powder has high fire resistance, resistance to attack by metal or non-metallic melts (erosion resistance), wear resistance,
It is stated that it is possible to obtain a film that has thermal shock resistance and is free of pores. However, producing thermal spray materials using this method requires the consumption of a large amount of electricity to generate plasma, making it uneconomical.Also, since it uses crystalline oxide powder as a raw material, The thermal spraying material obtained is also crystalline.Therefore, there are problems such as a high melting temperature and a large amount of thermal energy required for thermal spraying.

Therefore, the present inventors have developed an amorphous composite thermal spray material in which the components are uniformly composited and can form a coating with excellent properties such as wear resistance and corrosion resistance. We conducted extensive research to develop a manufacturing method.

[Means to solve the problem]

As a result, zirconium oxide and alumina have high temperature corrosion resistance and high wear resistance, respectively, but since a single coating has a high porosity, the corrosion resistance often decreases, but silica It has been found that the above problems can be solved by mixing and compounding. The present invention was completed based on this knowledge.

That is, in the present invention, the alumina is 45 to 70% by weight.

The present invention provides a composite thermal spray material comprising 1 to 50% by weight of silica and 5 to 50% by weight of zirconium oxide.

The reason why the proportions of each component in the composite thermal spray material of the present invention are determined as described above is as follows. Alumina (Aj!
gos) and zirconium oxide (ZrO,.

However, O<x≦2. Thermal spray materials produced using the above-mentioned materials (as described above) produce highly wear- and heat-resistant coatings, but these coatings have relatively high porosity and therefore have poor resistance to aggressive environments. , to which silica (SiO
By adding z), a dense and pore-free coating can be formed.

However, if only one component of 5tot is used, a good coating cannot be obtained because the strength of the coating is low and the heat resistance is also low. In addition, the zircon (ZrSiOn) coating is resistant to temperature changes, has good thermal insulation properties, and is suitable for molten glass materials,
Zircon has very good resistance to attack by slag and organic metals due to the low wettability of zircon by these melts. However, this coating also has a drawback of high porosity.

On the other hand, ALO coatings containing 5iOz also exhibit high wear resistance, and the presence of 5iOz improves corrosion resistance, but the drawback is that corrosion resistance often decreases due to high porosity. has.

Combining these facts, alumina is 45-70% heavy weight,
Weight: 50-70% by weight, 1-50% by weight of silica
, preferably 5 to 40% by weight and further comprising 5 to 50% by weight, preferably 10 to 30% by weight of zirconium oxide (ZrO*, O<X≦2), forms an excellent coating with low porosity. We have arrived at the knowledge that this is the case.

The present invention further relates to a method for producing the above thermal sprayed material,
It is characterized by mixing raw materials consisting of alumina sol, silica sol, and zirconium compound solution or zirconium oxide sol with water or an organic solvent to form a slurry, then spray-drying the slurry, and sintering the resulting spray-dried product. The present invention provides a method for manufacturing the above-mentioned thermal spray material.

The alumina sol used in the method of the present invention has a concentration of 1 to 50
Those containing %A2□03 by weight are preferred, and polar solvents such as water and alcohol can be used as the solvent, but among them, those containing water as the solvent are preferred.

The silica sol preferably contains 1 to 50% by weight of SiO□, and polar solvents such as water and alcohol can be used as the solvent, but those using water as the solvent are preferred.

Furthermore, various kinds of zirconium compounds can be used as the zirconium compound used in the method of the present invention, but zirconium salts such as chlorides, nitrates, and sulfates are preferred.

As a solvent for the zirconium compound, a polar solvent such as water or alcohol can be used, and it is particularly preferable to use water.

In the method of the present invention, a zirconium oxide sol can be used instead of a zirconium compound solution. Here, the zirconium oxide sol contains 1 to 50% by weight of Z
Those containing rO□ are preferred, and polar solvents such as water and alcohol can be used as the solvent, of which water is preferred.

In the method of the present invention, the above three components are mixed according to their concentrations in proportions such that the composition of the resulting composite powder falls within the range of the composite thermal spray material of the present invention described above, and the mixture is mixed with water or an organic solvent. It is desirable to lower the viscosity by adding (methanol, ethanol, etc.). The viscosity of this solution is preferably 200 cρ or less in order to improve feedability to the spray dryer.

After the slurry is prepared in this manner, the slurry is spray-dried. Various types of spray drying equipment can be used in this case. Of these, a rotating disk type is preferred. In addition, the hot air inlet temperature during spray drying is 7.
0 to 500°C, preferably 100'C or more,
In order to set the disk rotation speed to a particle size suitable for thermal spraying (1 am to 1 mm, preferably 1 to 100 μm), if the rotating disk diameter is 50 mm, for example, the rotation speed is 50,000 rpm (peripheral speed 131 μm).
m/sec) or less, preferably 40,000 rpm (peripheral speed 1
05m/sec) or less.

In the method of the present invention, the spray-dried product obtained by spray-drying the slurry as described above is further calcined.

This calcination is performed to remove anions (chloride ions, acetate ions, etc.) added as stabilizers for the alumina sol used as a raw material, and to remove anions of this compound when a zirconium compound solution is used. . The firing temperature at this time is generally 250 to 600"C,
Preferably it is 450-600°C. As for the atmosphere, it is preferable to bake in a steaming or reducing atmosphere rather than a completely oxidizing atmosphere. In such an atmosphere, zirconium does not become complete zirconium dioxide, but becomes an amorphous zirconium oxide powder represented by ZrOx (0<x≦2), which easily melts during thermal spraying.

The composite thermal spray material of the present invention obtained in this way uses a sol or an aqueous solution as a raw material, so EPMA (Ele
ctro Probe Micro Analysis
), it can be seen that alumina, silica, and zirconium oxide (ZrO, ) are uniformly present in the same powder and are a composite. Furthermore, when the powder was measured by X-ray diffraction, it was found to be in an amorphous state, and when the state of this powder was observed by XPS (X-ray photoelectron spectroscopy), it was found to be A/! It was found that , St, and Zr exist as their respective oxides, and there is no bond between metals. Further, the shape is spherical, and the particle size can be changed by changing the rotation speed of the spray drying disk.

For example, if the rotation speed is 50,000 rpm (peripheral speed 131 m/s), the average particle size will be about 5 μm, and the rotation speed will be 10,000 rpm.
pm (peripheral speed 26m/sec), the average particle size is 50μ
It will be about m. At this time, it is desirable that the powder used as a raw material be smaller in particle size than expected after spray drying.

The present invention further provides a thermal sprayed body formed by spraying the composite thermal spraying material onto a base material.

Various materials can be used as the base material for the thermal spray body, including metals, inorganic materials, and heat-resistant polymers. Here, metals include nickel, iron, copper, zinc,
Pure metals such as aluminum and alloys such as carbon steel, brass, and stainless steel can also be used. Inorganic materials include sintered bodies such as alumina, titania, silicon nitride, and silicon carbide, and these ceramics can also be used. Thermal spray coating.

Furthermore, glass or the like can also be used as a base material. Typical heat-resistant polymers include polyether nitrile, polyether sulfone, polyetherimide, polyphenylene sulfide, polyarylate polysulfone, and polyether ketone. It can also be applied to trees, bamboo, etc.

To spray the composite thermal spraying material onto this base material, use a powder type, plasma spraying, or explosive thermal spraying.

Flame spraying is available, and either method can form a good coating. However, among these, plasma spraying is the most preferred. This is because the high temperature in the plasma makes it possible to melt ceramics with a high melting point, and the spraying speed is also fast, so the bonding force between the base material and the sprayed coating is strong.
This is because a dense film can be formed. In addition, the working gas during thermal spraying is Ar, H, He, N, O, air, CH4
, CzHa.

A combination of one or more gases such as gaseous hydrocarbons such as C5Hs can be used.

In order to improve the adhesion between the coating formed by thermal spraying and the base material, it is preferable to perform blasting or the like on the surface of the base material before thermal spraying.

The coating formed by spraying the powder of the composite thermal spraying material of the present invention is resistant to thermal shock and can withstand cooling and heating cycles of 800°C, but in order to further increase the thermal shock resistance, it is effective to perform base thermal spraying. It is true. In this case, the material for base thermal spraying is:
Nickel-chromium alloy.

Suitable examples include nickel-aluminum composites, nickel-chromium-aluminum composites, nickel-chromium composites, aluminum-cobalt composites, and nickel-chromium-aluminum-cobalt-yttria composites. Further, in order to improve the corrosion resistance of the sprayed coating, it is preferable to perform a sealing treatment. Pore sealants include phenol resins, epoxy resins, polyurethane resins, silicone resins, and the like.

The thickness of the thermally sprayed coating is appropriately selected depending on the material, but is usually preferably 20 to 300 μm.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Colloidal silica (Si0□20% by weight, average particle size 20
mμ) 500 g, alumina sol (A l t 02
10% by weight, average particle size 100 mμ x 10 mμ) 2, 5
kg, zirconium nitrate aqueous solution (2.43 mol/f) 5
00m and water 2.51. were mixed at room temperature and stirred.

The viscosity of this mixed solution was 100 cp. Next, this solution was spray-dried (disc diameter: 50 cm, drying chamber diameter: 80 cm).
A spray drying device with a height of 1200 mm was used (disc circumferential speed 39 m/sec, temperature 250°C). The obtained powder was calcined in a Matsufuru furnace at 450°C for 2 hours.

The average particle size of this powder was 29 μm as measured by a laser diffraction particle size analyzer. Furthermore, this powder is EP
When observed with MA, S i O.

AI! ,□0. It was found that the powder was a uniform composite of Zr0X and Zr0X. Furthermore, when the zirconium oxide in the composition of this powder was analyzed by X-ray photoelectron spectroscopy (XPS), it was found that the value was between that of Zr and Zr0z. In addition, the composition of the powder was determined to be 5ich 2 by fluorescent X-ray analysis.
0 wt%, ALo, 50 wt% and ZrO, (ZrO□
) 30 weight. The composition of this composite powder is shown in Table 1.

This powder was plasma sprayed (thermal sprayer manufactured by Metco Co., Ltd. 1 working gas Ar/Nz) on an iron substrate.

Various physical property evaluations were performed on the obtained thermal spray coating.

The adhesion of the coating was determined by microscopically observing the cross section of the coating. Further, the hardness of the coating was measured using a Vickers hardness meter at a test load of 300 g. The thermal shock resistance test is
The coating was heated to 900'C and then immediately cooled with water. This cooling/heating cycle was repeated 20 times, and the coating was examined for peeling and damage caused by expansion and contraction of the base material due to heat. In the corrosion resistance test, the thermally sprayed coating was once sealed with phenol resin, and then the thermally sprayed piece was immersed in 5% hydrochloric acid for 360 hours, and damage and cracks in the coating were examined. The sample used in this test was
200 μm on the entire surface of a 50 square x 3 thick iron substrate
The weight change after the corrosion test was investigated.

These results are summarized in Table 2.

Example 2 In Example 1, the starting material was colloidal silica (Si
Oz20wt%) 1kg, alumina sol CA1.103
10% by weight) 2.5 kg, zirconium nitrate aqueous solution (
The same operation as in Example 1 was carried out, except that the amount of water was 0.81 mol/ff1) 500 d and 31 ml of water.

The composition of the composite powder obtained here is shown in Table 1. Further, the evaluation test for the coating was conducted in the same manner as in Example 1, and the results are summarized in Table 2.

Example 3 In Example 1, the starting material was colloidal silica (Si
0□20% by weight) 125g, alumina sol (Affi,
0310% by weight) 3.25 kg, 500 ml of zirconium nitrate aqueous solution (2.43 mol/f) and 3.0 ml of water! The same operation as in Example 1 was performed except for the following.

The composition of the composite powder obtained here is shown in Table 1. Further, the evaluation test for the coating was conducted in the same manner as in Example 1, and the results are summarized in Table 2.

Example 4 In Example 1, the starting material was colloidal silica (Si
0□20% by weight) 500g, alumina sol (/l□0,
10% by weight) 2.5kg, zirconia sol (Zr0□
1.5kg (10%, average particle size 25μm) and water 2.
The same operation as in Example 1 was carried out except that the value was changed to 51.

The composition of the composite powder obtained here is shown in Table 1. Further, the evaluation test for the coating was conducted in the same manner as in Example 1, and the results are summarized in Table 2.

Comparative Example 1 In Example 1, the starting material was alumina sol (Af, C
hlO weight%) 2.2! M! The same operation as in Example 1 was carried out, except that the aqueous solution of zirconium nitrate (2.43 mol//liter 917) and water 22 were used.

The composition of the composite powder obtained here is shown in Table 1. Further, the evaluation test for the coating was conducted in the same manner as in Example 1, and the results are summarized in Table 2.

Comparative Example 2 In Example 1, the starting material was colloidal silica (Si
Oz20% by weight) 825id and zirconium nitrate aqueous solution (2.43 mol/j 1111 ml),
The same operation as in Example 1 was performed.

The composition of the composite powder obtained here is shown in Table 1. Furthermore, the film evaluation test was conducted in the same manner as in Example 1, and the results are summarized in Table 2.

Comparative Example 3 In Example 1, the starting material was colloidal silica (Si
Oz20wt%) 575d, alumina sol CAltOs
10% by weight) 3.8! M! The same operation as in Example 1 was performed except that the amount of water was 3.51.

The composition of the composite powder obtained here is shown in Table 1. Further, the evaluation test for the coating was conducted in the same manner as in Example 1, and the results are summarized in Table 2.

Comparative example 4 250 g of α-alumina powder (average particle size 5 μm).

150 g of zirconia powder (average particle size: 3 μm) and 100 g of silica powder (average particle size: 3 μm) were simply physically mixed and sprayed under the same conditions as in Example 1. The subsequent treatments were carried out in the same manner as in Example 1. The composition of the composite powder obtained here is shown in Table 1.

Coatings sprayed using this powder did not have a uniform composition and had poor corrosion resistance.

Table 1 [Effects of the Invention] As mentioned above, since the composite thermal spray material of the present invention is in an amorphous state, it is easily melted and does not require a large amount of energy for thermal spraying. Moreover, since the thermal spray coating is formed from crystalline zirconium oxide and amorphous alumina and silica, it has high wear resistance and corrosion resistance.

Furthermore, since a sol or solution is used as a raw material, a thermal spray material containing a uniform composite of three components can be obtained, and the adhesion of the film is also excellent. Further, according to the method of the present invention, a thermal spray material having the above-mentioned excellent properties can be obtained at low cost since large electric power such as plasma is not used.

Therefore, the composite thermal sprayed material of the present invention is expected to be effectively used in the field of painting, maintenance of piping, etc., and surface modification of industrial materials.

Claims (2)

[Claims] (1) A composite thermal spray material consisting of 45-70% by weight of alumina, 1-50% by weight of silica, and 5-50% by weight of zirconium oxide. (2) Mixing water or an organic solvent with raw materials consisting of alumina sol, silica sol, and zirconium compound solution or zirconium oxide sol to form a slurry, then spray-drying the slurry, and sintering the resulting spray-dried product. A method for producing a composite thermal sprayed material according to claim 1.