CN1900357B - Process for local chemical plating long pipe surface - Google Patents

Abstract

The present invention relates to a partial chemical plating long tube whole or partial surface method used for raising inner bore surface coating uniformity and workpiece service life. Said method includes 1, adopts plating solution trough having electroless plating liquid, plating solution drive unit, connecting chemical plating long tube to form loop through pipe and valve; 2, starting up plating solution drive unit to fill chemical plating liquid in long tube simultaneously adopting heater relatively moving outside long tube to heat chemical plating liquid in long tube, making chemical plating to long tube inner surface; 3, continue circulation using chemical plating liquid back flown to plating solution trough until long tube inner surface whole or partial chemical plating ending. Heater and workpiece relatively move at 0.1-500mm/ min speed; chemical plating liquid continuously pass through workpiece inner bore at 0-500mm/ s speed.

Description

The method of partial electroless plating on the surface of long pipes

technical field

The invention relates to a method for locally chemically plating the surface of a long tube, which is a method for locally chemically plating all or part of the inner and outer surfaces of a long tube, and belongs to the technical field of chemical plating and anti-corrosion.

Background technique

Due to the limitation of the size of the plating tank in the traditional electroless plating process, the long tube cannot be chemically cleaned and electroless plated. Even if the size of the plating tank is large enough, it is difficult to ensure the circulation of the plating solution in the tube after the long tube reaches a certain length, which will affect the quality and uniformity of the coating in the inner hole.

JP63195279 discloses a method for first cleaning the inner hole of a workpiece, and then introducing an electroless plating solution for electroless plating. In this method, the electroless plating solution flows through the workpiece in one direction all the time. As the electroless plating solution flows through the surface of the workpiece, chemical deposition occurs continuously, accompanied by a series of chemical reactions, resulting in a concentration difference between the inflow end and the outflow end, so the thickness of the coating is inconsistent, which affects the quality of the coating.

CN1033593C discloses a method of electroless plating outside the tank, which can regularly and alternately change the flow direction of the electroless plating solution flowing through the workpiece, and improves the composition distribution of the plating solution in the inner hole of the workpiece. Coating with uniform thickness. Due to the concentration of the electroless plating solution at the entrance, the concentration of the plating solution changes as its deposition occurs, and the uniformity of the composition of the plating solution in the middle cannot be guaranteed, resulting in uneven thickness of the plating layer. In addition, if larger plating tank heating equipment is required for longer pipes, the composition gradient of the plating solution cannot be completely eliminated, which will make the thickness of the plating layer inconsistent, thus being limited.

Contents of the invention

The purpose of the present invention is to provide a method for partial electroless plating on the surface of long tubes, which can make the thickness of the coating on the surface of long tubes uniform, suitable for various long tubes, and the equipment used has high versatility, low cost, and is easy to automate Operation.

To achieve the above object, the present invention adopts the following technical solutions:

A method for local electroless plating on the surface of a long tube, characterized in that: the method comprises the steps of:

(1) Adopt the plating solution tank equipped with chemical plating solution, the plating solution driving device, and connect the long pipes to be chemically plated through pipelines and valves to form a circuit;

(2) Start the plating solution driving device to inject the chemical plating solution in the plating solution tank into the long tube, so that the chemical plating solution passes through the long tube and is filled in the long tube. The flow direction is relatively moved, and the electroless plating solution in the long tube is locally heated, so that the surface in the long tube is electroless plated;

(3) Continue to recycle the electroless plating solution returned to the plating solution tank until all or part of the electroless plating on the surface in the long tube is completed.

The heater heats the workpiece (long tube), but only locally heats a certain section of the long tube, that is, the heater heats the electroless plating solution in this section of the long tube, so that the temperature of the electroless plating solution in this section reaches The temperature of the electroless plating, so that the inner surface of the section is electroless plated. Due to the relative movement of the heater and the workpiece (long tube), the surface inside the long tube can be fully or partially electroless plated.

In the method for local electroless plating on the surface of a long tube of the present invention, in the step (2), the flow velocity of the electroless plating solution in the long tube is 0～500mm/s.

In the method for local electroless plating on the surface of the long tube of the present invention, the movement of the heater outside the long tube can be the following two ways of moving:

The first type of movement is: in the step (2), the movement of the heater outside the long tube is continuous movement, and the moving speed of the heater outside the long tube is 0.1-500mm/min.

The second way of moving is: in the step (2), the movement of the heater outside the long pipe is a step-by-step movement, that is, with the length of the heater used relative to a section in the long pipe, the length of the long pipe is heated. After one section, another section of the long tube is heated, and one section moves step by section.

The heating method of the heater is to wrap the entire heat source of the heater around the workpiece (long tube), that is, to make the workpiece (long tube) at the center of the temperature field of the heater.

The thickness of the coating is determined by the relative moving speed of the heater and the workpiece (long tube), the effective heating length of the heater (generally the length of the heater) and the flow rate of the electroless plating solution. When the thickness of the coating and the flow rate of the electroless plating solution are constant, the relative movement speed of the heater and the workpiece (long tube) is related to the effective heating length of the heater. The longer the effective heating length of the heater, the faster its relative movement speed ; On the contrary, it is slow.

The loading capacity is the ratio of the surface area ^dm2 of the workpiece (long tube) in the electroless plating solution to the volume L of the electroless plating solution, which is called the loading capacity or loading density. The smaller the loading capacity, the more the solution can provide enough metal ions deposition, so the flow rate can be very small.

The flow rate of the chemical plating solution is inversely proportional to the loading capacity of the effective heating length of the inner hole of the workpiece (long tube). When the loading capacity is small, the chemical plating solution can provide enough metal ions, and the flow rate of the chemical plating solution can be very small, or even 0; On the contrary, the electroless plating solution cannot provide enough metal ions, and the flow rate should be increased. In addition, the flow rate of the plating solution should not be too fast, otherwise the deposited coating particles will be washed away, the plating speed will be slowed down, and even cannot be deposited on the surface of the inner hole of the workpiece.

By controlling the relative moving speed of the heater and the workpiece (long tube) and the flow rate of the electroless plating solution, the thickness of the coating on the inner surface of the workpiece (long tube) can be controlled to obtain a coating with a thickness of 1-100 μm. The relative movement between the heater and the workpiece is completed, and the inner hole of the workpiece is finished with electroless plating.

In the method for partial electroless plating on the surface of a long tube of the present invention, in the step (2), the heater used keeps the temperature of the electroless plating solution in the long tube at 20-95°C. According to the chemical plating solution with different chemical composition, take different temperature.

In the method for partial electroless plating on the surface of a long tube of the present invention, in the step (2), the heater used is a resistance wire heating device, a water bath heating device, an infrared heating device, or a steam heating device.

In the method for partial electroless plating on the surface of a long tube of the present invention, in the step (1), the plating solution driving device used is a circulating pump, or a head tank and a pump, or an air pressure device.

In the method for partial electroless plating on the surface of a long tube of the present invention, in the step (1), the material of the long tube used is aluminum, copper, nickel, steel, aluminum alloy, copper alloy, nickel alloy.

In the method for partial electroless plating on the surface of a long tube of the present invention, in the step (1), the cross-sectional shape of the long tube used is circular, square or irregular.

In the method for local electroless plating on the surface of a long tube of the present invention, in the step (1), the cross-sectional shape of the long tube used is circular, and the diameter of the inner hole of the long tube is 1 to 1000mm, and the length of the long tube is The ratio to the inner hole is 10:1-10000:1.

In the method for local electroless plating on the surface of a long tube of the present invention, in the step (1), the cross-sectional shape of the long tube adopted is a square, and the side length of the inner square hole of the long tube is 1 to 1000mm. The ratio of the length to the side length of the inner square hole is 10:1~10000:1.

In the method for partial electroless plating on the surface of a long tube of the present invention, in the step (1), the electroless plating solution in the plating solution tank is a nickel, copper, tin or precious metal plating solution.

The method for local electroless plating on the surface of long pipes of the present invention can also be applied to composite coatings with more than two layers, that is, in the step (1), there are more than two plating solution tanks, which are equipped with different chemical plating tanks respectively. Plating solution, described plating solution tank is connected in parallel with long pipe by pipeline and valve respectively; The electroless plating solution of each plating solution tank carries out step (2) and step (3) successively according to the requirement of the specified composite plating solution layer Each layer of electroless plating until more than two layers of composite coatings are made. Clean with deionized water after each layer of electroless plating.

The method for local electroless plating long tube surface of the present invention can also be applicable to the chemical plating of long tube inner and outer surfaces, namely:

A method for local electroless plating on the surface of a long tube, the method comprising the steps of:

(1), the outside of the long tube to be chemically plated is covered with a layer of outer tube, using a plating solution tank equipped with chemical plating solution, a plating solution driving device, and forming a circuit through pipelines and valves, and the long tube, long tube and The jacket between the outer tubes is connected in parallel in the circuit;

(2) Start the plating solution driving device to inject the chemical plating solution in the plating solution tank into the long tube and the jacket, so that the chemical plating solution passes through the long tube and the jacket and is filled in the long tube and the jacket. At the same time, use heating The device moves relative to the flow direction of the chemical plating solution in the long tube and the jacket outside the outer tube, and locally heats the chemical plating solution in the long tube and the jacket, so that the surface inside and outside the long tube is electroless plated;

(3) Continue to recycle the chemical plating solution returned to the plating solution tank until all or partial chemical plating on the inner and outer surfaces of the long tube is completed.

The above method is that the jacket between the long tube and the outer tube shares a set of plating solution tank and plating solution driving device, and the same type of coating can be plated on the inner and outer surfaces of the long tube; the following method is that the jackets between the long tube and the outer tube use The plating solution tank and the plating solution drive device, the two plating solution tanks are equipped with different chemical plating solutions, which can be used to plate different kinds of coatings on the inner and outer surfaces of the long tube. The method of plating different coatings on the inner and outer surfaces of the long pipe is as follows:

A method for local electroless plating on the surface of a long tube, characterized in that: the method comprises the steps of:

(1), the outside of the long tube to be chemically plated is covered with a layer of outer tube, two sets of plating solution tanks and plating solution drive devices with different chemical plating solutions are used, and two sets of circuits are formed through pipelines and valves respectively, and the long The jackets between the pipe, the long pipe and the outer pipe are each connected in parallel in a set of circuits;

(2), respectively start the plating solution driving device to inject different chemical plating solutions in the plating solution tank into the corresponding long tubes and jackets, so that different chemical plating solutions pass through the long tubes and jackets respectively and fill the long tubes and jackets In the jacket, at the same time, the heater is used to move relative to the outside of the outer tube and the flow direction of the chemical plating solution in the long tube and the jacket, to locally heat the chemical plating solution in the long tube and the jacket, so that the inner and outer surfaces of the long tube are different. Electroless plating of plating solution;

(3) Continue to recycle the chemical plating solution returned to the plating solution tank until all or partial chemical plating on the inner and outer surfaces of the long tube is completed.

Therefore, the method for local electroless plating on the surface of a long tube of the present invention can be applied to the electroless plating on the surface of the long tube inside, outside, and inside and outside (the inner and outer coatings can be the same or different).

The method of the invention can be used for chemical plating and also for chemical cleaning, that is, the chemical plating liquid is replaced with chemical cleaning liquid.

The invention is a method for partial electroless plating of all or part of the surface of a long tube. Through the relative movement between the heater and the workpiece (long tube), the composition gradient of the electroless plating solution is eliminated, and the deposition area of the coating is controlled, thereby ensuring that the inner hole The coating is uniform. This method is suitable for preparing various conventional tubes or special-shaped tubes with a diameter of 1-1000 mm, and can be applied to aerospace, petroleum, chemical, electric power, pharmaceutical and other industries, and has a wide range of applications.

The method of the present invention is applicable to all tubular and similar tubular devices, such as pipes, tube radiators and the like. It is suitable for all materials that can be electroless plated, such as aluminum, copper, nickel, steel and other materials and their alloys.

The advantage of the present invention is that it breaks through the traditional overall chemical plating method, adopts the method of partial chemical plating on the surface of the long tube, and controls the chemical plating on the surface of the inner hole (or outside, or inside and outside) of the long tube by controlling the temperature and flow rate of the chemical plating solution. In the area, the composition gradient of the chemical plating solution in the workpiece can be avoided, so that the thickness of the coating in the inner hole of the workpiece is uniform. In addition, the present invention is suitable for various long pipes, and the ratio of the length to the inner hole can be from 10:1 to 10000:1, or even larger. The equipment has high versatility, low cost, and easy automatic operation.

Example 1

An aluminum tube with a diameter of 3.0mm and a length of 3m is used as the blank, and after degreasing, pickling, and zinc dipping treatment, the electroless nickel-phosphorus alloy is plated. Alkaline nickel-phosphorus pre-plating is performed first, and then acidic electroless nickel-phosphorus alloy plating is performed. The formula and process of the mature electroless plating solution are as follows:

Alkaline bath:

NiSO ₄ 6H ₂ O 30g/L

NaH ₂ PO ₂ ·H ₂ O 10g/L

Sodium citrate 100g/L

Ammonium chloride 50g/L

The pH value is 8.5-9.5, the temperature is 40-45°C, and the time is 5 minutes;

Acid bath:

NiSO ₄ 6H ₂ O 25g/L

NaH ₂ PO ₂ H ₂ O 24g/L

Lactic acid 25ml/L

Boric acid 20g/L

The pH value is 4.5-5.0, the temperature is 80-95°C, the time is 60 minutes, the flow rate of the plating solution is 5-10mm/s, and the relative moving speed between the heater and the workpiece is 10-15mm/min.

Two plating solution tanks respectively equipped with the above-mentioned alkaline plating solution and acidic plating solution, and a cleaning tank equipped with deionized water are used, and the circulation pump, pipeline and valve are respectively connected in parallel with the aluminum pipe (workpiece) to form a circuit. The heater adopts a sleeve-shaped resistance wire heating device, and the heating device wraps a section of the aluminum tube.

First perform alkaline pre-plating of nickel and phosphorus, open the outlet valve of the alkaline plating solution tank, start the circulation pump, inject the alkaline plating solution in the alkaline plating solution tank into the aluminum tube, make the alkaline plating solution pass through the aluminum tube and fill the In the tube, at the same time, a resistance wire heating device is used outside the aluminum tube, from one end of the aluminum tube to the other end, to move relative to the flow direction of the alkaline plating solution in the tube, and heat the alkaline plating solution in the tube. The heating temperature of the solution is 40-45°C, the flow rate of the alkaline plating solution is 5-10mm/s, and the relative moving speed of the heater and the aluminum tube is 120-130mm/min. The alkaline plating solution is recycled until all or part of the electroless plating on the surface of the aluminum tube is completed, the circulation pump and the outlet valve of the alkaline plating solution tank are closed, and the alkaline pre-plating of nickel and phosphorus is completed.

Then, rinse with deionized water. Open the outlet valve of the ionized water cleaning tank, start the circulation pump, and make the ionized water pass through the aluminum tube for cleaning. After cleaning, close the outlet valve of the circulating pump and the ion water cleaning tank.

Carry out acidic electroless nickel-phosphorus alloy plating again, open the outlet valve of the acid plating solution tank, start the circulation pump, make the acid plating solution in the acid plating solution tank inject in the aluminum tube, make the acid plating solution pass through the aluminum tube and be filled in the tube, at the same time, A resistance wire heating device is used outside the aluminum tube, from one end of the aluminum tube to the other end, to move relative to the flow direction of the acidic plating solution in the tube, and heat the acidic plating solution in the tube, wherein the heating temperature of the acidic plating solution is 80-95 ℃, the flow rate of the acidic plating solution is 5-10mm/s, and the relative moving speed between the heater and the aluminum tube is 10-15mm/min. The acidic plating solution is recycled until all or part of the surface of the aluminum tube is finished, and the cycle is closed. Pumps, and outlet valves of acid baths, acidic electroless nickel-phosphorus alloy finish.

The 3m-long aluminum tube was cut into 10 sections, and the thickness of the coating was determined to be 10±1μm, and then the tube was cut open by wire cutting, and it was found that there was a uniform coating on the surface of the inner hole.

Example 2

Use a pure aluminum special-shaped tube with a diameter of 3.0mm and a length of 12m as the blank instead of the 3m long aluminum tube in Example 1, the flow rate of the plating solution is 15-30mm/s, and the rest are carried out according to the conditions in Example 1. Cut the 12m long pipe into 20 sections, the thickness of the coating is measured to be 15±1μm, and there is a uniform coating on the surface of the inner hole.

Example 3

Use a pure aluminum special-shaped tube with a diameter of 5.0 mm and a length of 1 m as the blank instead of the 3 m long aluminum tube in Example 1, the flow rate of the plating solution is 500 mm/s, and the rest are carried out according to the conditions in Example 1. Cut the 1m-long pipe into 4 sections, the thickness of the coating is measured to be 3±0.5μm, and there is a uniform coating on the surface of the inner hole.

Example 4

Be that the pure aluminum tube of 200.0mm in diameter, long 2.2m is blank to replace the 3m long aluminum tube in embodiment 1, after plating solution is filled in the pure aluminum tube, flow velocity is 0mm/s, all the other according to the condition in embodiment 1 conduct. Cut the 2.2m long pipe into 5 sections, the thickness of the coating is measured to be 6±1μm, and there is a uniform coating on the surface of the inner hole.

Example 5

Using a 1Cr18Ni9Ti stainless steel pipe with a diameter of 2.0mm and a length of 5m, first carry out alkali cleaning, pickling, and activation on the inner hole of the stainless steel pipe, and then electroless nickel plating. Its electroless nickel plating solution is as follows:

NiSO ₄ 6H ₂ O 22g/L

NaH ₂ PO ₂ H ₂ O 14g/L

CH ₃ COONa·3H ₂ O 10g/L

_CH3COOH 7g/L

Thiourea 0.002g/L

The pH value is 4.0-5.0, the temperature is 80-95°C, the time is 60 minutes, the flow rate of the plating solution is 15-30mm/s, and the step-by-step movement is adopted, and the electroless plating time of each section is 60 minutes.

The specific process is as follows:

The plating solution tank equipped with the above electroless nickel plating solution is used to connect with 1Cr18Ni9Ti stainless steel pipes (workpieces) respectively through circulating pumps, pipelines and valves to form a loop. The heater adopts a sleeve-shaped resistance wire heating device, and the sleeve-shaped resistance wire heating device encloses a section of the stainless steel pipe.

Open the outlet valve of the plating solution tank, start the circulating pump, inject the electroless nickel plating solution in the plating solution tank into the stainless steel tube, make the electroless nickel plating solution pass through the stainless steel tube and fill the tube, and at the same time, use a resistance wire heating device outside the stainless steel tube , from one end of the stainless steel tube to the other end, relative to the flow direction of the electroless nickel plating solution in the tube, and the heater moves the stainless steel tube step by step, that is, heating a section of the stainless steel tube and then heating the next section of the stainless steel tube, Step-by-step movement one after another. Among them, the heating temperature of the electroless nickel plating solution is 80-95°C, the flow rate of the electroless nickel plating solution is 15-30mm/s, and the electroless plating time of each section (that is, the heating time of the heater in each section) The electroless nickel plating solution is recycled for 60 minutes until all or part of the electroless plating on the surface of the stainless steel tube is completed, the circulation pump and the outlet valve of the plating solution tank are closed, and the electroless nickel plating is completed.

Cut the stainless steel pipe into 10 sections, the thickness of the coating is measured to be 12±1μm, and there is a uniform coating on the surface of the inner hole.

Example 6

The stainless steel tube in Example 5 was replaced by a nickel-plated aluminum tube with a diameter of 3.0 mm and a length of 1.5 m (with a coating of 10 μm), the inner hole was cleaned, and then electroless copper plating. Its electroless copper plating solution is as follows:

CuSO ₄ 5H ₂ O 10g/L

Formaldehyde (37%) 20ml/L

EDTA sodium salt 20g/L

NaOH 10g/L

Methyldichlorosilane 0.25g/L

The pH value is 11.5-12.5, the temperature is 55-65°C, the time is 60 minutes, the flow rate of the plating solution is 15-30 mm/s, and the step-by-step movement is adopted, and the electroless plating time of each section is 60 minutes. Except above-mentioned process condition, its processing specific process is the same as embodiment 5.

Cut the aluminum tube into 5 sections, the thickness of the composite coating is measured to be 15±1μm, and there is a uniform copper coating on the surface of the inner hole.

Example 7

A nickel-plated aluminum tube with a diameter of 3.0 mm and a length of 2 m (coating layer 10 μm) was used instead of the aluminum tube in Example 1, the inner hole was cleaned, and then Ni-P/Al ₂ O ₃ was plated chemically. Its electroless plating solution is as follows:

NiSO ₄ 6H ₂ O 20g/L

NaH ₂ PO ₂ H ₂ O 24g/L

Lactic acid 20ml/L

Propionic acid 5ml/L

KIO ₃ 2mg/L

Al ₂ O ₃ 6g/L

The pH value is 4.5-5.0, the temperature is 80-85° C., and the time is 60 minutes. The flow rate of the plating solution and the moving speed of the heater are the same as the acidic plating solution in Example 1.

The specific process is as follows:

The plating solution tank equipped with the above-mentioned chemical composite Ni-P/Al ₂ O ₃ solution is used to connect with the nickel-plated aluminum pipe (workpiece) through a circulation pump, pipeline and valve respectively to form a circuit. The heater adopts a sleeve-shaped resistance wire heating device, and the sleeve-shaped resistance wire heating device wraps a section of the nickel-plated aluminum tube.

Open the outlet valve of the plating solution tank, start the circulation pump, inject the chemical plating solution in the plating solution tank into the nickel-plated aluminum tube, make the chemical nickel plating solution pass through the nickel-plated aluminum tube and fill the tube, and at the same time, use a resistance wire heating device to The outside of the nickel-plated aluminum tube moves from one end to the other end of the nickel-plated aluminum tube relative to the flow direction of the chemical plating solution in the tube, and heats the chemical plating solution in the tube. The heating temperature of the chemical plating solution is 80-85°C. The flow rate of the electroless plating solution is 5-10 mm/s, and the relative moving speed of the heater and the nickel-plated aluminum tube is 10-15 mm/min. The plating solution is recycled until all or part of the electroless plating on the surface of the nickel-plated aluminum tube is completed, and the circulation pump and the outlet valve of the electroless plating solution tank are closed to complete.

The aluminum tube was cut into 5 sections, the thickness of the composite coating was determined to be 20±1 μm, and the coating contained Al ₂ O ₃ according to energy spectrum analysis.

Claims (11)

1. the method for a local chemical plating long pipe surface, it is characterized in that: this method comprises the steps:

(1), adopts bath trough that chemical plating fluid is housed, plating bath drive unit and the long tube of want electroless plating is connected and composed the loop by pipeline and valve;

(2), starting the plating bath drive unit injects the chemical plating fluid in the bath trough in the long tube, make chemical plating fluid by long tube and be filled in the long tube, simultaneously, adopt well heater chemical plating fluid flow direction in long tube outside and long tube to relatively move, to the chemical plating fluid local heating in the long tube, make the surface in the long tube carry out electroless plating, the velocity of flow of chemical plating fluid in long tube is 0～500mm/s, well heater is that continous way moves the mobile of long tube outside, the translational speed of well heater in the long tube outside is 0.1～500mm/min, perhaps well heater is that stepped start-stop system moves the mobile of long tube outside, promptly with one section in the relative long tube of length of the well heater that adopted, another section of reheat long tube after one section of the heating long tube, one section connects one section stepped start-stop system and moves, and it is 20～95 ℃ that the well heater that is adopted makes the temperature of the chemical plating fluid in the long tube;

(3), the chemical plating fluid that will be back to bath trough continues to recycle, till the surface in long tube all or local chemical plating finishes.

2. the method for local chemical plating long pipe surface according to claim 1, it is characterized in that: in described step (2), the well heater that is adopted is resistance wire heating unit, heating in water bath device, infrared heating device or steam heater.

3. the method for local chemical plating long pipe surface according to claim 1, it is characterized in that: in described step (1), the plating bath drive unit that is adopted is recycle pump or header tank and pump or pneumatic shuttle.

4. the method for local chemical plating long pipe surface according to claim 1, it is characterized in that: in described step (1), the material of the long tube that is adopted is aluminium, copper, nickel, iron and steel, aluminium alloy, copper alloy, nickelalloy.

5. the method for local chemical plating long pipe surface according to claim 1 is characterized in that: in described step (1), the cross-sectional shape of the long tube that is adopted is for circular, square or special-shaped.

6. the method for local chemical plating long pipe surface according to claim 5, it is characterized in that: in described step (1), the cross-sectional shape of the long tube that is adopted is for circular, and the diameter of bore of long tube is 1～1000mm, and the length of long tube and the ratio of endoporus are 10: 1～10000: 1.

7. the method for local chemical plating long pipe surface according to claim 5, it is characterized in that: in described step (1), the cross-sectional shape of the long tube that is adopted is square, and the interior square hole length of side of long tube is 1～1000mm, and the ratio of the length of long tube and the interior square hole length of side is 10: 1～10000: 1.

8. the method for local chemical plating long pipe surface according to claim 1, it is characterized in that: in described step (1), the chemical plating fluid in the described bath trough is nickel, copper, tin or precious metal plating bath.

9. the method for local chemical plating long pipe surface according to claim 1, it is characterized in that: in described step (1), described bath trough is more than two, and different chemical plating fluids is housed respectively, and described bath trough is in parallel with long tube by pipeline and valve respectively; The chemical plating fluid of each bath trough divides the electroless plating of successively carrying out each layer of step (2) and step (3) by the requirement of the composite plating bath layer of defined, till the composite deposite of making more than two-layer.

10. the method for a local chemical plating long pipe surface, it is characterized in that: this method comprises the steps:

(1), the long tube outside of want electroless plating is surrounded by one deck outer tube, adopt bath trough that chemical plating fluid is housed, plating bath drive unit and constitute the loop, and the chuck between long tube, long tube and outer tube is connected in parallel in the described loop by pipeline and valve;

(2), starting the plating bath drive unit injects the chemical plating fluid in the bath trough in long tube and the chuck, make chemical plating fluid by long tube and chuck and be filled in long tube and chuck in, simultaneously, adopt well heater chemical plating fluid flow direction in outside pipe and long tube and chuck to relatively move, to the chemical plating fluid local heating in long tube and the chuck, make the inside and outside surface of long tube carry out electroless plating, the velocity of flow of chemical plating fluid in long tube is 0～500mm/s, well heater is that continous way moves the mobile of long tube outside, the translational speed of well heater in the long tube outside is 0.1～500mm/min, perhaps well heater is that stepped start-stop system moves the mobile of long tube outside, promptly with one section in the relative long tube of length of the well heater that adopted, another section of reheat long tube after one section of the heating long tube, one section connects one section stepped start-stop system and moves, and it is 20～95 ℃ that the well heater that is adopted makes the temperature of the chemical plating fluid in the long tube;

(3), the chemical plating fluid that will be back to bath trough continues to recycle, until the surface inside and outside the long tube all or till local chemical plating finishes.

11. the method for a local chemical plating long pipe surface is characterized in that: this method comprises the steps:

(1), the long tube outside with want electroless plating is surrounded by one deck outer tube, adopt and two to be set with the bath trough of different chemical plating bath and plating bath drive unit, and constitute two cover loops by pipeline and valve respectively, and the chuck between long tube, long tube and outer tube respectively is connected in parallel in the cover loop;

(2), starting the plating bath drive unit respectively injects the different chemical plating bath in the bath trough respectively in pairing long tube and the chuck, make the different chemical plating bath respectively by long tube and chuck and be filled in long tube and chuck in, simultaneously, adopt well heater chemical plating fluid flow direction in outside pipe and long tube and chuck to relatively move, to the chemical plating fluid local heating in long tube and the chuck, make the inside and outside surface of long tube carry out the electroless plating of different plating baths, the velocity of flow of chemical plating fluid in long tube is 0～500mm/s, well heater is that continous way moves the mobile of long tube outside, the translational speed of well heater in the long tube outside is 0.1～500mm/min, perhaps well heater is that stepped start-stop system moves the mobile of long tube outside, promptly with one section in the relative long tube of length of the well heater that adopted, another section of reheat long tube after one section of the heating long tube, one section connects one section stepped start-stop system and moves, and it is 20～95 ℃ that the well heater that is adopted makes the temperature of the chemical plating fluid in the long tube;

(3), the chemical plating fluid that will be back to bath trough continues to recycle, until the surface inside and outside the long tube all or till local chemical plating finishes.