CN101588656B - A TiO2-based ceramic heating coating for heating rollers and its preparation method - Google Patents

Abstract

The invention discloses a _TiO2- based ceramic heating coating for a heating roller and a preparation method thereof, belonging to the field of thermal spraying in material processing engineering. The ceramic coating provided by the present invention includes an insulating layer (1) sprayed directly on the roller core (S), and a heating layer (2) sprayed on the insulating layer (1) and in close contact with the insulating layer (1). ). Both the insulating layer (1) and the heating layer (2) are sprayed by plasma spraying equipment. The ceramic coating used for heating rollers provided by the present invention and its preparation method can effectively solve the problems of complex auxiliary equipment and uneven heating required by other heating rollers, and can be heated at a higher temperature, and has the advantages of fast heating, energy saving, environmental protection, Uniform temperature, safety and other characteristics.

Description

A TiO₂-based ceramic heating coating for heating rollers and its preparation method

technical field

The invention belongs to the field of thermal spraying in material processing engineering, and in particular relates to a _TiO2- based ceramic heating coating for a heating roller prepared by a plasma spraying method and a preparation method thereof.

Background technique

Many production processes such as lamination, embossing, drying, annealing, calendering and film orientation in the papermaking, printing, printing, copying, textile, rubber, plastic, chemical fiber and other industries require the use of heated rollers, especially for sheet reels Such products are preheated, dried, oriented, laminated, embossed, embossed, etc., and are more suitable for heating or processing the processed products with heating rollers.

At present, the heating methods of the heating roller mainly include liquid heating and electric heating. Among them, liquid heating methods such as oil, water, and steam are traditional heating methods, which have been used for decades. Most liquid heating systems require liquid storage tanks and heating equipment, and pumps, rotary contactors, and pipes are required to transfer liquids to Roller. Due to its high maintenance cost, difficulty in temperature control, high energy consumption, easy leakage and corrosion, and regular maintenance of pressure vessels, it has been less and less used by people.

Electric heating is mainly divided into two methods: electric heating tube direct heating and electromagnetic induction heating. The direct heating of the electric heating tube is to put the electric heating tube directly into the heating roller, so that the heat is evenly distributed on the surface of the roller to achieve the purpose of heating; the electromagnetic induction heating is to use a high frequency generator to drive the induction heating coil, through the induction heating and heat pipe technology Heat is generated by passing the inner surface of the roll shell through a high-intensity, rapidly changing magnetic field. Because electric heating has unique advantages in environmental protection, service life, safety performance, etc., it has become more and more popular and has become the main heating method for heating rollers. However, because this heating method requires additional electric heating tubes and induction auxiliary equipment, the cost is high, and the heating temperature on the surface of the roller is not easy to control uniformly, which affects the product quality, and it is difficult to meet the requirements for some products with high requirements. At the same time, due to its complex structure, it brings difficulties to temperature detection, resulting in low precision of temperature control, which also affects the quality of products.

Ceramic heating roller is a new type of electric heating roller. It uses thermal spraying technology to directly spray various ceramic materials on the outer surface of the roller to form a thin and uniform heating element with special functions covering the entire roller surface. Through An external power source generates uniform radiant heat on the roll surface. Since the ceramic heating roller adopts external heating, heat is generated directly on the surface of the roller, so that the surface temperature of the ceramic heating roller is higher than the internal temperature, so this external heating system is more efficient than other internal heating systems, greatly reducing System power consumption. At the same time, due to the high hardness of the ceramic coating, good corrosion resistance, wear resistance, stable chemical properties, and not easy to oxidize, the ceramic heating roller has high production efficiency, good product quality, uniform heating, easy temperature control, and reduces equipment maintenance. cost and downtime, long service life, energy savings, safe operation and the same performance as higher cost induction heated rolls. At present, there is no relevant report on ceramic heating rollers in China.

Contents of the invention

The object of the present invention is to provide a _TiO2- based ceramic heating coating for heating rollers and a preparation method thereof. The coating provided by the invention can meet the application in a higher temperature range and meet the industrial requirements of low current and high voltage. The addition of Al ₂ O ₃ can obviously increase the heating temperature of the coating, so that the coating can work stably above 300°C.

A kind of _TiO2 base ceramic heating coating for heating roller provided by the present invention comprises an insulating layer directly sprayed on the roller core, and a heating layer sprayed on the insulating layer and in close contact with the insulating layer; The material used for the insulating layer is an insulating ceramic material: Al ₂ O ₃ powder, with a thickness of 120-150 μm; the material used for the heating layer is a ceramic material with semiconductor characteristics: a mixed powder of TiO ₂ +Al ₂ O ₃ , wherein, The TiO ₂ and Al ₂ O ₃ powders are mixed in a mass percentage of 90:10-50:50, and the thickness of the heating layer is 180-200 μm.

A kind of TiO that the present invention is provided is used for the preparation method of the _TiO base ceramic coating of heating roller, comprises the following steps:

1) Spraying of the insulating layer: Use plasma spraying equipment to spray Al ₂ O ₃ powder, the material of the insulating layer, on the roller core after sandblasting and roughening treatment. The spraying process parameters are: main gas Ar, main gas flow rate 32~ 45L/min, auxiliary gas H ₂ , auxiliary gas flow rate 8~10L/min, powder feeding gas Ar, powder feeding gas flow rate 10~12L/min, powder feeding rate 25~40g/min, current 500~550A, gun swing speed 25~30mm/s, the speed of the test piece is 200~300 rpm, and the spraying distance is 90~110mm.

2) Spraying of the heating layer: use plasma spraying equipment to spray the material TiO ₂ +Al ₂ O ₃ powder of the heating layer on the insulating layer, wherein, TiO ₂ and Al ₂ O ₃ powders are 90:10-50 by mass percentage : 50 mixed; spraying process parameters are: main gas Ar, main gas flow rate 40-42L/min, auxiliary gas H ₂ , auxiliary gas flow rate 3-9L/min, powder feeding gas Ar, powder feeding gas flow rate 10-12L/min , The powder feeding rate is 30-50g/min, the current is 550-600A, the gun swing speed is 25-30mm/s, the specimen speed is 200-300 rpm, and the spraying distance is 90-110mm.

In the TiO ₂ -based ceramic heating coating for heating rollers according to the present invention, the resistance of the heating layer is adjusted by adjusting the ratio of TiO ₂ and Al ₂ O ₃ .

A kind of _TiO2 base ceramic heating coating for heating roller and preparation method thereof according to the present invention can be sprayed on the roller core made of steel, stainless steel, brass, aluminum, glass or FRP synthetic material, especially Roll cores made of steel material.

The advantages of the present invention are:

According to the preparation method proposed in the present invention, the prepared _TiO2- based ceramic heating coating for the heating roller is subjected to a power-on heating test. With the increase of power, the surface temperature of the heating roller can reach more than 300 ° C, and it can be energized for a long time , There is no abnormal change in the coating system of the heating roller.

The ceramic coating for the heating roller provided by the present invention can effectively solve the problem of complex auxiliary equipment and uneven heating required by other heating rollers, and can be heated at a higher temperature, and has the advantages of fast heating, energy saving, environmental protection, uniform temperature, safety, etc. features.

Description of drawings

Fig. 1 is a schematic cross-sectional view of the ceramic heating coating of the present invention. Among them, s is the roller core, 1 is the insulating layer, 2 is the heating layer, and 3 is the electrode copper sheet.

Fig. 2 is a schematic diagram of the structure of the ceramic heating coating of the present invention.

Fig. 3 is the ceramic heating coating power curve with temperature of the present invention

Detailed ways

The present invention will be further elaborated below in conjunction with the accompanying drawings and specific embodiments.

In the following examples, No. 20 low-carbon steel pipes with a length of 150 mm, a diameter of 32 mm, and a wall thickness of 3 mm are selected as the roll core s, and the insulating layer 1 and the heating layer 2 are sprayed successively on the roll core s. The electrode copper sheet 3 has a structure as shown in FIG. 2 .

The Al ₂ O ₃ powder and TiO ₂ powder used in the following examples are commercially available. Wherein the Al ₂ O ₃ powder has a purity of over 98% and a particle size of 20-40 μm, and the TiO ₂ powder has a purity of over 98% and a particle size of 20-40 μm. The ratio of TiO ₂ and Al ₂ O ₃ in the heating layer is shown in Table 1.

Table 1 Ceramic heating coatings with different proportions of TiO ₂ and Al ₂ O ₃

Example 1

1) Use plasma spraying equipment to spray the insulating layer 1 on the surface of the steel pipe that has been roughened by sandblasting. The material of the insulating layer 1 is Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow 32L/min, auxiliary gas Air H ₂ , auxiliary gas flow rate 8L/min, powder feeding gas Ar, powder feeding gas flow rate 10L/min, powder feeding rate 25g/min, current 550A, gun swing speed 25mm/s, specimen speed 300 rpm, spraying The distance is 90 mm, and the thickness of the insulating layer 1 is 120 μm;

2) Use plasma spraying equipment to spray the heating layer 2 on the surface of the insulating layer 1. The material of the heating layer 2 is 90wt.% TiO ₂ +10wt.% Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow rate 40L /min, auxiliary gas H ₂ , auxiliary gas flow rate 6L/min, powder feeding gas Ar, powder feeding gas flow rate 10L/min, powder feeding rate 30g/min, current 550A, gun swing speed 25mm/s, specimen speed 300 rpm /min, the spraying distance is 90mm, and the thickness of the heating layer 2 is 180μm. The room temperature resistance of the heating layer 2 is 21.70Ω. Electrode copper sheets 3 are added to the two ends of the heating layer 2 with a width of about 1 cm, so that the heating layer 2 and the electrodes 3 are in close contact. Carry out an electrical test on the heating roller, the heating roller can be heated to 330°C, and there is no abnormal change in the coating system of the heating roller. See the TA10 curve in Figure 3 for the variation of ceramic heating coating power with temperature.

Example 2

1) Use plasma spraying equipment to spray the insulating layer 1 on the surface of the steel pipe that has been roughened by sandblasting. The material of the insulating layer 1 is Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow 32L/min, auxiliary gas Air H ₂ , auxiliary gas flow rate 8L/min, powder feeding gas Ar, powder feeding gas flow rate 10L/min, powder feeding rate 25g/min, current 550A, gun swing speed 25mm/s, specimen speed 300 rpm, spraying The distance is 100 mm, and the thickness of the insulating layer 1 is 120 μm;

2) Use plasma spraying equipment to spray the heating layer 2 on the surface of the insulating layer 1. The material of the heating layer 2 is 80wt.% TiO ₂ +20wt.% Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow rate 40L /min, auxiliary gas H ₂ , auxiliary gas flow rate 6L/min, powder feeding gas Ar, powder feeding gas flow rate 10L/min, powder feeding rate 30g/min, current 550A, gun swing speed 25mm/s, specimen speed 300 rpm /min, the spraying distance is 100 mm, and the thickness of the heating layer 2 is 180 μm. The room temperature resistance of the heating layer 2 is 72.30Ω. Electrode copper sheets 3 are added to the two ends of the heating layer 2 with a width of about 1 cm, so that the heating layer 2 and the electrodes 3 are in close contact. Carry out an electrification test on the heating roller, the heating roller can be heated to 360°C, and there is no abnormal change in the coating system of the heating roller. The power of the ceramic heating coating varies with temperature, as shown in the TA20 curve in Figure 3.

Example 3

1) Use plasma spraying equipment to spray the insulating layer 1 on the surface of the steel pipe that has been roughened by sand blasting. The material of the insulating layer 1 is Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow rate 35L/min, auxiliary Air H ₂ , auxiliary gas flow rate 9L/min, powder feeding gas Ar, powder feeding gas flow rate 11L/min, powder feeding rate 35g/min, current 525A, gun swing speed 27mm/s, specimen speed 250 rpm, spraying The distance is 100 mm, and the thickness of the insulating layer 1 is 140 μm;

2) Use plasma spraying equipment to spray heating layer 2 on the surface of insulating layer 1. The material of heating layer 2 is 70wt.% TiO ₂ +30wt.% Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow rate 42L /min, auxiliary gas H ₂ , auxiliary gas flow rate 3L/min, powder feeding gas Ar, powder feeding gas flow rate 12L/min, powder feeding rate 45g/min, current 600A, gun swing speed 27mm/s, specimen speed 250 rpm /min, the spraying distance is 100 mm, and the thickness of the heating layer 2 is 195 μm. The room temperature resistance of the heating layer 2 is 143.5Ω. Electrode copper sheets 3 are added to the two ends of the heating layer 2 with a width of about 1 cm, so that the heating layer 2 and the electrodes 3 are in close contact. Carry out an electrification test on the heating roller, the heating roller can be heated to 360°C, and there is no abnormal change in the coating system of the heating roller. See the TA30 curve in Figure 3 for the variation of ceramic heating coating power with temperature.

Example 4

1) Use plasma spraying equipment to spray the insulating layer 1 on the surface of the steel pipe that has been roughened by sand blasting. The material of the insulating layer 1 is Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow rate 45L/min, auxiliary Air H ₂ , auxiliary gas flow rate 10L/min, powder feeding gas Ar, powder feeding gas flow rate 12L/min, powder feeding rate 40g/min, current 500A, gun swing speed 25mm/s, specimen speed 300 rpm, spraying The distance is 100 mm, and the thickness of the insulating layer 1 is 150 μm;

2) Use plasma spraying equipment to spray heating layer 2 on the surface of insulating layer 1. The material of heating layer 2 is 60wt.% TiO ₂ +40wt.% Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow rate 42L /min, auxiliary gas H ₂ , auxiliary gas flow rate 9L/min, powder feeding gas Ar, powder feeding gas flow rate 12L/min, powder feeding rate 40g/min, current 550A, gun swing speed 25mm/s, specimen speed 300 rpm /min, the spraying distance is 100mm, and the thickness of the heating layer 2 is 190μm. The room temperature resistance of the heating layer 2 is 80.30Ω. Electrode copper sheets 3 are added to the two ends of the heating layer 2 with a width of about 1 cm, so that the heating layer 2 and the electrodes 3 are in close contact. Carry out an electrification test on the heating roller, the heating roller can be heated to 490°C, and there is no abnormal change in the coating system of the heating roller. See the TA40 curve in Figure 3 for the variation of ceramic heating coating power with temperature.

Example 5

1) Use plasma spraying equipment to spray the insulating layer 1 on the surface of the steel pipe that has been roughened by sand blasting. The material of the insulating layer 1 is Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow rate 45L/min, auxiliary Gas H ₂ , auxiliary gas flow rate 10L/min, powder feeding gas Ar, powder feeding gas flow rate 12L/min, powder feeding rate 40g/min, current 500A, gun swing speed 30mm/s, specimen speed 200 rpm, spraying The distance is 110 mm, and the thickness of the insulating layer 1 is 150 μm;

2) Use plasma spraying equipment to spray heating layer 2 on the surface of insulating layer 1. The material of heating layer 2 is 50wt.% TiO ₂ +50wt.% Al ₂ O ₃ powder. The spraying process parameters are: main gas Ar, main gas flow rate 42L /min, auxiliary gas H ₂ , auxiliary gas flow rate 6L/min, powder feeding gas Ar, powder feeding gas flow rate 12L/min, powder feeding rate 50g/min, current 600A, gun swing speed 30mm/s, specimen speed 200 rpm /min, the spraying distance is 110 mm, and the thickness of the heating layer 2 is 200 μm. The room temperature resistance of the heating layer 2 is 131.20Ω. Electrode copper sheets 3 are added to the two ends of the heating layer 2 with a width of about 1 cm, so that the heating layer 2 and the electrodes 3 are in close contact. Carry out an electrical test on the heating roller, the heating roller can be heated to 450°C, and there is no abnormal change in the coating system of the heating roller. See the TA50 curve in Figure 3 for the variation of ceramic heating coating power with temperature.

Claims (3)

1. a kind of TiO that is used for heating roller _Base ceramic heating coating is characterized in that, comprises the insulating layer (1) that is directly sprayed on the roller core (S), and is sprayed on the insulating layer (1) with A heating layer (2) in close contact with the insulating layer (1); Among them, the insulating layer (1) is composed of Al ₂ O ₃ powder with a thickness of 120-150 μm; the heating layer (2) is composed of TiO ₂ +Al ₂ O ₃ powder, and the purity of Al ₂ O ₃ powder is 98% Above, the particle size is 20-40 μm, the purity of TiO ₂ powder is more than 98%, the particle size is 20-40 μm, TiO ₂ and Al ₂ O ₃ powder are mixed in a mass percentage of 90:10-50:50, and the heating layer ( 2) The thickness is 180 to 200 μm. 2. a kind of TiO that is used for heating roller according to claim ₁ The preparation method of base ceramic heating coating is characterized in that, comprises the following steps: 1) Spraying of the insulating layer (1): Use plasma spraying equipment to spray Al ₂ O ₃ powder, the material of the insulating layer (1), on the roller core after sandblasting and roughening treatment. The spraying process parameters are: main gas Ar, main gas flow rate 32-45L/min, auxiliary gas H ₂ , auxiliary gas flow rate 8-10L/min, powder feeding gas Ar, powder feeding gas flow rate 10-12L/min, powder feeding rate 25-40g/min, current 500～550A, gun swing speed 25～30mm/s, specimen speed 200～300 rpm, spraying distance 90～110mm; 2) Spraying of the heating layer (2): Spray the material TiO ₂ +Al ₂ O ₃ powder of the heating layer (2) onto the insulating layer (1) using plasma spraying equipment, wherein the purity of the Al ₂ O ₃ powder is The purity of the TiO ₂ powder is more than 98%, the particle size is 20-40 μm, the purity of the TiO 2 powder is more than 98%, the particle size is 20-40 μm, and the TiO ₂ and Al ₂ O ₃ powders are mixed in a mass percentage of 90:10-50:50; Spraying process parameters are: main gas Ar, main gas flow rate 40-42L/min, auxiliary gas _H2 , auxiliary gas flow rate 3-9L/min, powder feeding gas Ar, powder feeding gas flow rate 10-12L/min, powder feeding rate 30-50g/min, current 550-600A, gun swing speed 25-30mm/s, specimen speed 200-300 rpm, spraying distance 90-110mm. 3. A TiO ₂ -based ceramic heating coating for heating rollers according to claim 1, characterized in that the resistance of the heating layer (2) is adjusted by adjusting the ratio of TiO ₂ and Al ₂ O ₃ .

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