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Application of Titanium Equipment in Electroplating Production

1.Application of titanium serpentine tube heating in electroplating production
Electroplating is widely used in machinery, instrumentation, aviation, shipbuilding and other manufacturing industries, as well as daily necessities and other various equipment production.
The corrosion of electroplating bath heating process equipment and some problems in electroplating wastewater treatment have affected the output and quality of electroplating, increased the consumption of energy and materials, and caused serious pollution to the environment.
At the beginning of 1960s, titanium heater, anode net blue and thin film evaporator were used in electroplating production abroad, and the effect was very good.
In the 1970s, titanium serpentine tube heaters were used in China, and the anode net was blue; For example, Shanghai No.3 Bicycle Factory and Beijing Jikou Factory have adopted titanium film evaporator to recycle electroplating wastewater, and achieved good results.
Application of 1 titanium serpentine tube heater in electroplating production
Applications:Nickel plating, chromium plating (except fluoride chromium plating), acid and cyanide copper plating, ferric chloride copper plate corrosion and other bath heating.
(1) Heating mode of electroplating bath solution
The heating mode of bath liquid consists of external heating type (i.e.water jacket heating) and internal heating type.In the past, most electroplating workshops in China used water jacket heating.Water jacket heating is complicated, with low thermal efficiency and large gas consumption.At the same time, under the strong corrosive medium and high temperature steam vibration, the lead-lined plate or plastic-lined plate quickly corrodes and ages, resulting in leakage and leakage, which seriously pollutes the electroplating solution and affects the quality of plated parts.
In view of the shortcomings of water jacket heating, many electroplating workshops in China, such as Xi'an Railway Signal Factory and Xi'an Bicycle Factory, have changed from water jacket heating to internal heating, and adopted industrial pure titanium to make serpentine heaters.
Table 1 of economic effects of two heating methods is as follows.It can be seen from the table that the titanium serpentine tube is very corrosion-resistant, long-life, fast heat transfer and good heating effect.Heating a 2000-liter electroplating bath solution can save 63 tons of steam, with a value of 378 yuan.

Table 1 Economical comparison of titanium heaters with water jacket heating (in 2000 liters) Titanium serpentine tube heater
Project
category
Work Rangeheating time
(hours)
steam consumption
kg/hour
annual savings
steam
service lifeeffect of plating
mediumtemperature ℃
water jacket
lined lead plate
standard plating
cr.ni
50 ~ 60Er" width="72"> 375/2 ~ 3with
water jacket
liner steel
Standard plating
Cr.Ni
50 ~ 602 ~ 370/1 ~ 2have

Standard plating
Cr.Ni
50 ~ 6015063 tonn/378 yuanmore than 10 yearsNone

2) Heater material
Electroplating solutions produced by electroplating nickel, chromium and acidic copper have strong corrosivity.In the past, the heater was made of iron pipe wrapped with lead, lead-antimony alloy pipe, 1Cr18Ni9Ti and industrial enamel, which could not meet the technological requirements.Its disadvantages are:
(1) The heating effect of iron pipe wrapped with lead and lead-antimony alloy pipe is poor and the gas consumption is large.At the same time, white lead sulfate precipitate will be generated, which will pollute the electroplating solution and affect the quality of plated parts;
(2) The iron pipe is wrapped with plastic, which not only has slow heat transfer, but also ages and peels off quickly at high temperature, and the iron pipe is exposed and corroded rapidly.
3.1Cr18Ni9Ti is corroded and perforated in half a month.
④ Industrial enamel will be stripped and corroded when it is slightly impacted.
Since 1974, many domestic units have successively used titanium serpentine tube heaters in nickel plating, chromium plating and acid copper plating, and achieved good results.
Economic comparison of titanium with 1Cr18Ni9Ti and lead-antimony alloy tube heaters Table 2.As can be seen from Table 2, titanium heaters have the following advantages:
(1) Corrosion resistance, long service life, with a preliminary estimated service life of more than ten years;
Fast heat transfer and good heating effect;
③ Titanium has high strength and is not afraid of collision;
No pollution to the product;
The labor productivity is improved and the maintenance cost is reduced.

Table 2 Economic comparison of heaters made of different materials (calculated by 2 gauge pressure, volume 2000 liters) Align="center" width="84"> 50
Project
Heater material
specification
outside diameter × wall thickness × length

(mm)
working rangeheating time
(hours)
steam consumption
kg/hour
price
(Yuan/unit)
Lifetime
MediaTemperature ℃
Lead and antimonyφ 40 × 5 × 12000Standard Ni plating45 ~ 55/708002 years
1Cr18Ni9Tiidth="143"> φ 25 × 2 × 12000Standard Ni plating45 ~ 551.560609101 month
pure titaniumφ 20 × 1.5 × 12000standard Ni plating45 ~ 55111400over ten years
Lead and antimonyφ 40 × 5 × 12000Standard Cr plating50 ~ 603708002 ~ 3 years
1Cr18Ni9Tiφ 25 × 2 × 12000Standard Cr Plating50 ~ 60260910Half a month
Pure titaniumφ 20 × 1.5 × 12000Standard Cr plating50 ~ 601501400More than ten years

II.Application of anode net blue in electroplating production
Application:Nickel plating, acid copper plating, etc.
In the production of nickel plating and acid copper plating in many electroplating workshops in China in the past, due to the direct dissolution of anode plates, the annual loss of thin nickel and copper anode plates accounted for almost one quarter of the consumption of nickel and copper anode plates in the whole electroplating workshop.This loss is quite amazing.
Application of 1 titanium anode mesh blue
Since 1973, Guangdong Electroplating Factory, Shanghai No.3 Bicycle Factory, Xi'an Bicycle Factory, Shaanxi Sewing Machine Factory and other units have successively applied anode net blue to nickel plating and acid copper plating, and the recovery rate of anode plate has reached 100%.For example, in Shaanxi Sewing Machine Factory, when nickel is plated every year, a total of 6136 kg of nickel anode plates are consumed, and 1534 kg of thin nickel anode plates are scrapped.After using titanium anode net blue, 1534 kg of thin nickel anode plate can be recycled every year, with a value of 42952 yuan.At the same time, it not only makes full use of the quick fining of nickel, but also makes the inner surface of many electroplated special-shaped workpieces electroplated because of the uniform current distribution, which improves the quality of plated parts.
Many domestic electroplating workshops have used round iron wrapping plastic and microporous plastic plate to make anode net blue, which can not meet the technological requirements.Its disadvantages are:
(1) Iron-wrapped plastic board, due to the aging and peeling of plastic at high temperature, the exposed garden iron corrodes rapidly, and its life is only 1-2 months.At the same time, it also pollutes the electroplating solution and affects the quality of plated parts.
② Microcellular plastic plate, because the plastic is not conductive, needs to add nickel rod or copper rod, conductive rod and anode block are dissolved together, and it should be stopped for replacement frequently.Moreover, microcellular plastic has poor mechanical strength, and it will break after slight impact during operation, which affects normal production.
Since 1973, Guangdong Electroplating Factory, Shanghai No.3 Bicycle Factory, Tianjin Bicycle Factory, Xi'an Bicycle Factory and Shaanxi Sewing Machine Factory have successively applied titanium anode net blue to nickel plating and acid copper plating, and achieved good results.
TD>

Th="120"> 400 × 60 × 900

30 ~ 401 ~ 2 monthsHave



Titanium meshAcid copper plating20 ~ 4020 ~ 40400 ~ 500over ten yearsNone

III.Electroplating hangers
A) Overview
Aluminum and its alloys are coated with an oxide film with a thickness of 100 ~ 200 angstroms under natural conditions, which has poor corrosion resistance.Thicker oxide films can be formed on their surfaces by electrolytic or anodic oxidation treatment and chemical oxidation treatment, which can effectively prevent corrosion.
The growth process of film on anode is due to two processes, and the anodic oxidation electrolyte is sulfuric acid, chromic acid and oxalic acid solution.Table 4 lists the main working conditions of anodizing aluminum and its alloys.In the anodizing process of aluminum and its alloys, the unreasonable material selection of hanging tools seriously affects the output and quality.Conventional hangers are made of central columns or shelves, with contacts made of stainless steel of various shapes, and the surface of the hangers is protected by polyethylene.These materials have many shortcomings in use.Although brass has good electrical conductivity, it dissolves quickly when the polyethylene protective coating is broken.At the same time, stainless steel contacts are often disconnected.Generally speaking, the traditional brass/stainless steel hanger is only used for about 6 months, and the coating is peeled off or the contact point is broken.Therefore, it is necessary to find a material with both corrosion resistance and good electrical conductivity to make the hanger.
It is reported that titanium hanger has been used in anodizing aluminum and its alloys since 1977 in the United States, and achieved good results.

Table 4 Main parameters of anodizing treatment of aluminum and its alloys

voltage
(volts)

Current required
type
electrolytecurrent density
(amps/decimeter 2 )
electrolyte temperature
(℃)

nameMolecular formulaContent
(%)

DCSulfuric acidH 2 SO 4 20 ~ 25="96"> 8 ~ 300.5 ~ 310 ~ 35
CommunicationSulfuric acidH 2 SO 4 " 84"> 20 ~ 2510 ~ 151 ~ 318 ~ 25
DCOxalic acidH 2 C 2 O 4 to 1030 ~ 601 ~ 218 ~ 30
CommunicationOxalic acidH 2 C 2 O 4 530 ~ 801 ~ 520 ~ 45
DCChromic anhydrideCr 2 O 3 5 ~ 1020 ~ 500.5 ~ 2.520 ~ 40

2 basis for selecting titanium hangers
The hanger should have sufficient corrosion resistance and good electrical conductivity to meet the requirements of anodic oxidation process.
(1) Stability of surface film
Although titanium is a very active metal, its standard electrode potential is negative than that of zinc, but it is easy to combine with oxygen to form oxide film, and its stability in many media exceeds that of aluminum and stainless steel, so it is extremely difficult to dissolve.When the titanium hanger is anodized in sulfuric acid solution, a more stable anodic passivation film will be formed on the surface of titanium under a certain positive potential, and almost no corrosion will be caused under anodic oxidation conditions.Therefore, titanium hanger has good corrosion resistance in anodic oxidation treatment of aluminum and its alloys.
(2) Conductivity
Although the conductivity of titanium hanger is low, it is only 3.1% compared with copper.However, the conductivity of titanium hanger immersed in solution is more than 6 times higher than that in air, and the conductivity of titanium hanger connected with brass cathode is also greatly improved.Therefore, the conductivity of titanium hanger in the production of anodizing aluminum and its alloy can meet the production process requirements.
Application of 3 titanium hanger
It is reported that titanium hanger has been applied to anodizing aluminum and its alloys in sulfuric acid and chromic acid since 1977 in American electroplating industry.Over the past two years, it is still in normal use.Practice has proved that titanium hanger is corrosion resistant; The surface of titanium hanger does not need polyethylene protective coating; The electrical conductivity meets the production process requirements; The whole titanium hanger is light and strong, and is convenient to use in the production process.
At present, titanium hangers have hardly been used in anodizing aluminum and its alloys in China's electroplating industry.Based on a series of advantages of titanium hanger, especially from the comprehensive economic effect, the application of titanium hanger in anodic oxidation treatment of aluminum and its alloys is of great significance to overcome various disadvantages of brass/stainless steel hanger, and it is an important task of technical reform in electroplating industry.
4.Titanium anode hook for electropolishing
Electropolishing is to anodize the surface of metal in a special electrolyte under certain specifications.
In the electropolishing process of small workpiece, the anode hook is usually immersed in the highly corrosive electropolishing solution together with the workpiece.Selective corrosion solution occurs in polishing solution to achieve polishing purpose, while the hook itself is conductive and resistant to corrosion of polishing solution, and does not dissolve in repeated use all the year round.
In the past, in many electroplating workshops in China, the output and quality were affected because of the unreasonable hook materials.The polishing solution and process conditions used in shanghai hairdressing tool factory are shown in table 5

Main process parameters of electropolishing
Electrolyte composition
(per liter)
Voltage
(V)
Current density
(amps/decimeter)
Temperature
(℃)
Sulfuric acidphosphoric acidchromic anhydride
50 ml900 ml280 grams2010 ~ 20100 ~ 105

In the past, they used brass anode hooks.Brass dissolved quickly when copper was charged in the above medium, and it was corroded and fractured after several times of use.Although lead is corrosion resistant, it has low strength and inelasticity, so it is not suitable for hanging hooks.
In 1973, the factory used φ 3 mm pure titanium as anode hook, which is still in normal use.Practice has proved that titanium hook is corrosion resistant in electropolishing, has no influence on products, improves productivity and reduces labor intensity, and has remarkable effect.

Source:Excerpt from http://www.cdxgt.com


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