Chemical nickel plating of zinc die casting
Zinc die-cast Zinc alloy die casting is short. In the surface treatment of zinc die-casting will often problems like: sparkling, over corrosion.
Zinc alloy handle for the performance of the hardness, wear resistance is increased? Is to be on the electroless nickel plating of zinc die casting. However, due to gender shaped the zinc must be special treatment.
The first is process analysis. Two kinds of typical process: ¢Ù ¡ú weak alkali degreasing corrosion (1% H2SO4) ¡ú activation (pyrophosphate) ¡ú pre ¡ú neutral nickel-plated electroless nickel plating ¡ú heat treatment; ¢Ú water spray loss (1% ~ 20% H2SO4 , 10 ~ 15s) ¡ú ¡ú Pre-warm neutral nickel plating ¡ú (citric acid 1 ~ 2g / L, 80 ~ 90 ¡æ, 1min) ¡ú ¡ú heat treatment of electroless nickel plating.
Then pre-plated nickel-neutral. Neutral Nickel formula 1 #: nickel sulfate 160 ~ 180g / L, sodium citrate 192 ~ 216g / L, sodium chloride 10 ~ 16g / L, boric acid 25 ~ 30g / L; pH = 7, DK = 4A/dm2, 45 ¡æ, ¡Ý 20min. Recipe # 2: nickel sulfate 100 ~ 180g / L, sodium citrate 130 ~ 200g / L, sodium chloride 15 ~ 20g / L, boric acid 30 ~ 40g / L, additive A3ml / L; pH = 7 ~ 7.5, DK = 1 ~ 1.5A/dm2, the impact of the current 2 ~ 4A/dm2, the impact of time of 5 ~ 7min, 50 ~ 60 ¡æ, 20 ~ 25min, the cathode move 20 to 30 times / min.
Pre-plated nickel-neutral should be noted are: ¢Ù the use of nickel-sulfate-based pre-salt bath, close to the composition of electroless nickel plating. pH value should be controlled at around 7 to 7.5. ¢Ú to ensure there is sufficient thickness of the bottom, to improve the quality of the underlying. If the additive formula 2 # A, can improve the bottom and the substrate binding, the appearance becomes smooth and detailed, finished product rate of 95% or more. ¢Û proper handling of the solution produced by Ni (OH) 2 precipitate, the plating bath recovery capabilities. Such as the way to the bath with a siphon in the upper part of the lower part of the precipitate and separate the serum, then with dilute sulfuric acid or citric acid to precipitate dissolved, then mix the solution of two parts, with 5% NaOH to adjust pH to the specified value.
There is, for its heat treatment, the hardness of electroless nickel plating layer can be adjusted by heat treatment, the organization remains non-crystalline, so that the underlying content distribution tends to be uniform, and from the matrix began to have a small amount of phosphorus, so that the substrate and coating binding better, more uniform and fine organization, raise the degree of dispersion, the coating surface finish, Aluminum Casting coating corrosion resistance, wear resistance were all improved. Considering the low melting point zinc alloy, in order to prevent deformation of the workpiece, with the end of heat treatment temperature for a long time, such as 220 ¡À 5 ¡æ, 5h microhardness increased by 5 times. It was also used 180 ¡æ ¡Á 1h heat treatment conditions.
Zinc alloy handle for the performance of the hardness, wear resistance is increased? Is to be on the electroless nickel plating of zinc die casting. However, due to gender shaped the zinc must be special treatment.
The first is process analysis. Two kinds of typical process: ¢Ù ¡ú weak alkali degreasing corrosion (1% H2SO4) ¡ú activation (pyrophosphate) ¡ú pre ¡ú neutral nickel-plated electroless nickel plating ¡ú heat treatment; ¢Ú water spray loss (1% ~ 20% H2SO4 , 10 ~ 15s) ¡ú ¡ú Pre-warm neutral nickel plating ¡ú (citric acid 1 ~ 2g / L, 80 ~ 90 ¡æ, 1min) ¡ú ¡ú heat treatment of electroless nickel plating.
Then pre-plated nickel-neutral. Neutral Nickel formula 1 #: nickel sulfate 160 ~ 180g / L, sodium citrate 192 ~ 216g / L, sodium chloride 10 ~ 16g / L, boric acid 25 ~ 30g / L; pH = 7, DK = 4A/dm2, 45 ¡æ, ¡Ý 20min. Recipe # 2: nickel sulfate 100 ~ 180g / L, sodium citrate 130 ~ 200g / L, sodium chloride 15 ~ 20g / L, boric acid 30 ~ 40g / L, additive A3ml / L; pH = 7 ~ 7.5, DK = 1 ~ 1.5A/dm2, the impact of the current 2 ~ 4A/dm2, the impact of time of 5 ~ 7min, 50 ~ 60 ¡æ, 20 ~ 25min, the cathode move 20 to 30 times / min.
Pre-plated nickel-neutral should be noted are: ¢Ù the use of nickel-sulfate-based pre-salt bath, close to the composition of electroless nickel plating. pH value should be controlled at around 7 to 7.5. ¢Ú to ensure there is sufficient thickness of the bottom, to improve the quality of the underlying. If the additive formula 2 # A, can improve the bottom and the substrate binding, the appearance becomes smooth and detailed, finished product rate of 95% or more. ¢Û proper handling of the solution produced by Ni (OH) 2 precipitate, the plating bath recovery capabilities. Such as the way to the bath with a siphon in the upper part of the lower part of the precipitate and separate the serum, then with dilute sulfuric acid or citric acid to precipitate dissolved, then mix the solution of two parts, with 5% NaOH to adjust pH to the specified value.
There is, for its heat treatment, the hardness of electroless nickel plating layer can be adjusted by heat treatment, the organization remains non-crystalline, so that the underlying content distribution tends to be uniform, and from the matrix began to have a small amount of phosphorus, so that the substrate and coating binding better, more uniform and fine organization, raise the degree of dispersion, the coating surface finish, Aluminum Casting coating corrosion resistance, wear resistance were all improved. Considering the low melting point zinc alloy, in order to prevent deformation of the workpiece, with the end of heat treatment temperature for a long time, such as 220 ¡À 5 ¡æ, 5h microhardness increased by 5 times. It was also used 180 ¡æ ¡Á 1h heat treatment conditions.
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