JPH03177555A - Formed body - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance and wear resistance of parts as base material by forming a plastic layer excellent in corrosion resistance and a sprayed deposit of hard material, such as ceramics and cermet, excellent in wear resistance on the surface of parts as base material composed of carbon steel, etc. CONSTITUTION:For example, a cylindrical roll made of carbon steel for a paper-making machine is used as a base material 1, and a plastic sheet consisting of thermosetting resin or thermoplastic resin and excellent in corrosion resistance is allowed to adhere to the surface of the above base material 1 by means of an adhesive, by which a plastic layer 2 having a thickness, e.g. of several tens micrometers to several centimeters is formed. Further, a thermally sprayed layer 3 consisting of high-hardness ceramics or cermet of oxide type, carbide type, nitride type, boride type, etc., is formed on the above layer 2 to a thickness, e.g. of hundreds micrometers to several centimeters. By this method, the parts made of metal excellent in corrosion resistance as well as in wear resistance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a molded article suitable for use as various members and parts requiring corrosion resistance and wear resistance.

"Prior Art" Various members and parts that are used in corrosive atmospheres, such as in liquids and gases such as water, seawater, acids, and alkalis, and that also require wear resistance, such as rolls of paper manufacturing machines. and liners, conveyor pulleys installed outdoors, dehydrator rolls, agitator impellers and types, etc., and construction materials such as concrete tiles, plastic tiles, plastic sheets, corrugated boards, concrete tiles, and wall materials. In the case of vehicle bodies such as automobiles and trains, it is common to subject the surface of the base material to a surface treatment to increase corrosion resistance and wear resistance.

For example, taking the rolls of a paper manufacturing machine as an example, (A) the surface of a steel roll that provides strength is plated with hard chrome, which has corrosion resistance, and (B) the surface of a steel roll is thermally sprayed to provide wear resistance. (C) Using a corrosion-resistant stainless steel roll, the surface is coated with wear-resistant ceramic by thermal spraying. Those with , etc. are used.

However, all of the above solutions have the following drawbacks.

In other words, with the plating described in (A) above, it is impossible to completely eliminate small pinholes (communicating holes reaching from the surface of the plating layer to the base material) and cracks from the hard chrome plating layer. Corrosive liquids and gases penetrate into the base material through pinholes and cracks, causing localized corrosion. Further, the corrosion resistance of hard chrome itself is inferior to that of ceramics, and the hardness is about Hv800, which is much lower than the Hv2000 of ceramics, and its wear resistance is also greatly inferior. Furthermore, since the surface of hard chrome plating is smooth, it is not suitable for cases where a large coefficient of friction is required to prevent slipping or the like. Furthermore, since the size of the base material is limited by the size of the wood, the processing cost becomes very high if the size is large.

In addition, in the thermal spray coating described in (B) above, a solution in which plastic is dissolved in a solvent is used as the sealing solution, but the pinholes in the thermal spray coating can be small, with a diameter of several micrometers or less. It is impossible to completely seal the pinhole to the bottom, and only the surface portion is sealed. If polishing is performed after the sealing process, most of the sealing portion will be removed, reducing corrosion resistance. .

Furthermore, the use of the stainless steel roll (C) above increases costs because stainless steel is expensive and has poor weldability and machinability.

In addition, it is inferior to ceramics in its corrosion resistance, as it causes pitting corrosion when exposed to seawater.

The present invention was made in view of the above circumstances, and has corrosion resistance,
The object of the present invention is to provide a molded article that has excellent wear resistance, is inexpensive, and is suitable for use as various members and parts used in corrosive atmospheres.

"Means for Solving the Problems" The present invention is characterized in that a base material having a plastic layer having corrosion resistance on its surface is covered with a thermal spray coating made of ceramic or cermet having corrosion resistance and wear resistance. It is.

"Function" When the base material does not have corrosion resistance, the molded product of the present invention can be formed by forming a corrosion-resistant plastic layer on the surface of the base material, and then covering the plastic layer with a thermal spray coating. Ru. Alternatively, when the base material itself has a corrosion-resistant plastic layer on its surface, it is formed by covering the surface with a thermal spray coating.

The above-mentioned glasstic layer mainly exhibits corrosion resistance, and the above-mentioned thermal spray coating mainly exhibits wear resistance, and both of them ensure sufficient corrosion resistance and abrasion resistance of the base material.

"Example" An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a cross section of a molded body used as a roll in a paper manufacturing machine, for example. This roll has a cylindrical molded base material 1 made of carbon steel that provides strength, and a plastic layer 2 formed on the outer peripheral surface of the base material 1. , which is a plus.

The plastic layer 2 may be made of thermosetting resin such as phenol resin, urea resin, melamine resin, or unsaturated polyester resin, or may be made of polyethylene, polypropylene, saturated polyester resin, polystyrene, polyvinyl chloride, acrylate plastic, or nylon. , polyacetal resin, polycarbonate, or other thermoplastic resin. The thickness of the plastic layer 2 is preferably several tens of microns to several centimeters, and the type of resin and the thickness of the layer may be selected depending on the type of corrosion-resistant atmosphere.

The above plastic layer 2 can be formed by bonding a sheet-like material to the base material 1 with an adhesive, or by pre-forming it into a tube shape with an inner diameter slightly larger than the outer diameter of the base material 1. It is necessary to eliminate pinholes by applying methods such as attaching the tube to the outside and heating it to shrink the tube so that it fits tightly, or by spraying melted plastic powder onto the surface of the base material l using thermal spraying. .

On the other hand, the above thermal spray coating 3 can be made of various ceramics, such as oxide ceramics such as alumina, titania, alumina/titania, zirconia, silicon oxide, and chromium oxide, and carbide ceramics such as chromium carbide, titanium carbide, tungsten carbide, and silicon carbide. , nitride ceramics such as titanium nitride, zirconium nitride, and hafnium nitride, boride ceramics such as chromium boride, zirconium boride, and molybdenum boride, and various cermets such as tungsten carbide + cobalt, titanium carbide + cobalt, It is made of silicon carbide + nickel, etc. The thickness of this sprayed coating 3 is several hundred microns.
The thickness is preferably from m to several cm, and the type of powder and layer thickness may be selected depending on the required degree of wear resistance.

The thermal spray coating 3 is formed by thermal spraying such as high-velocity gas spraying, plasma spraying, and explosive thermal spraying. In the case of ceramics, since the melting point is high, plasma spraying with a high flame temperature is preferable.

To explain the case using the plasma spraying method, the plasma gun is placed 150 to 200 mm away from the surface of the plastic layer 2, and the plasma gun is moved in the axial direction of the base material 1 while rotating the base material 1 to perform thermal spraying. , a thermally sprayed coating 3 of ceramic or cermet may be formed on the entire surface of the plastic layer 2. In this case, the flame temperature of the plasma is as high as 15,000°C on average, so the powder (melting point 2,000-3, OO0°C) blown into the flame is instantly melted at a high speed (300-700 rm/ 5
ec) and collides with the surface of the plastic layer 2 to form a coating 3. And the temperature gradient of the flame is very large.
50 degrees away from the cathode of the plasma gun, the temperature drops to 1°500°C, and furthermore, it is air-cooled by the time it reaches the plastic layer 2, and the surface of the plastic layer 2 is cooled by blowing compressed air. The powder size is small, several tens of microns, and its heat capacity is low, so the melting point is 90-3.
Even if the plastic layer 2 has a low temperature of about 00'O, the plastic layer 2 will not melt and can be thermally sprayed sufficiently.

After the formation of the sprayed coating 3 is completed, if the surface needs to be smooth, the coating 3 can be polished with a diamond grindstone, but if a rough surface is better, it can be used as is without polishing. . Since the surface roughness of the sprayed coating 3 is about Ra3 to R&10, the surface as sprayed is suitable for slip prevention.

As mentioned above, in a roll in which the plastic layer 2 is formed on the surface of the base material 1 and the thermally sprayed coating 3 is formed on the surface, corrosive liquid or gas passes through the pinholes in the thermally sprayed coating 3 on the surface. It penetrates to plastic layer 2, but since there are no pinholes or cracks in plastic layer 2,
The corrosive liquid or gas is stopped at the surface of the plastic layer 2 to prevent corrosion of the base material l. Note that the thermal spray coating 3 and the plastic layer 2 have strong corrosion resistance by themselves, and therefore will not corrode.

In addition, since the thermal spray coating 3 is dotted with pores (voids) with a diameter of several μm, its Vickers hardness appears to be above 800~
Although it shows a value of 1500Hv, the true hardness of the particles themselves constituting the thermal sprayed coating 3 is as high as 2000 to 3000Hv, so it shows great wear resistance.

As described above, in the roll described above, each layer is responsible for corrosion resistance and wear resistance, that is, the plastic layer 2 is mainly responsible for corrosion resistance, and the thermal spray coating 3 is mainly responsible for wear resistance. It has ideal corrosion resistance and wear resistance.

In the above case, it goes without saying that polishing the sprayed coating 3 will not affect the corrosion resistance in any way, and since alumina has insulation properties and titania has antistatic properties, both A roll having a thermal spray coating 3 consisting of the above naturally has insulation properties and anti-static properties. Furthermore, the pores in the thermal spray coating 3 can provide surface properties such as improved paper separation properties on stone rolls that come into contact with wet paper.

The above-mentioned molded products are scratch-resistant and have strong weather resistance, so they can be used not only as rolls for paper manufacturing machines but also in a wide variety of applications, such as building materials and automobile bodies. It is.

In the above example, the plastic layer 2 was first formed on the surface of the base material 1, and the thermal spray coating 3 was formed thereon. However, regarding the formation of the plastic layer 2 and the thermal spray coating 3, the thermal spray coating 3 may be wrapped around the base material 1 and adhered thereto, or a split type plastic segment on which the thermal sprayed coating 3 has been sprayed in advance may be adhered to the base material 1.

Further, the cross-sectional shape of the molded body may be various shapes such as an ellipse or a rectangle, and the material of the base material 1 may be various such as wood, concrete, or plastic. If the base material 1 itself is made of plastic having corrosion resistance, the thermal spray coating 3 may be directly formed on its surface and the plastic layer 2 may be omitted.

Furthermore, the plastic layer 2 and the thermal spray coating 3 are not limited to being formed on the entire outer surface of the base material 1, but may be formed only on necessary parts.

"Effects of the Invention" As explained in detail above, the present invention provides a material in which a base material having a corrosion-resistant plastic layer on its surface is covered with a thermally sprayed coating made of ceramic or cermet that has corrosion resistance and wear resistance. Therefore, the plastic layer has corrosion resistance equal to or higher than that of ceramics, has no pinholes or cracks, and can completely protect the base material from the corrosion-resistant atmosphere. Abrasion resistance is ensured.

Thermal spray coatings can form a wide range of coatings at high speed and at low cost, regardless of the material, shape, and dimensions of the base material. By changing the conditions, the surface roughness and porosity of the sprayed coating can be adjusted, giving the surface a desired coefficient of friction, creating a surface with good separation from the other material, and even improving insulation properties. It is also possible to add special surface properties such as anti-static properties.
There is an advantage.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example in which the molded article of the present invention is applied to a roll. l...Base material, 2...Plastic layer,
3...Thermal spray coating.

Claims (1)

[Claims] The base material has a plastic layer with corrosion resistance on the surface.
A molded article characterized by being covered with a thermally sprayed coating made of ceramic or cermet having corrosion resistance and wear resistance.