Causes and solutions for missing black edges of electroless nickel barrel plating steel parts:
(1) Low sinking speed
The pH value of the plating solution is too low: Measure the pH value and adjust it, and control the pH at the lower limit. Although a higher pH value can increase the sinking speed, it will affect the stability of the plating solution.
The temperature of the plating solution is too low: the bath is required to be applied when the temperature reaches the specification. Plating. When the first batch of workpieces are put into the tank in a newly opened cylinder, the temperature should reach the upper limit. After the reaction starts, during normal plating, the temperature should be at the lower limit.
The concentration of the main component of the solution is low: analyze and adjust, such as When the reducing agent is insufficient, add reducing replenishing solution; when the nickel ion concentration is low, add nickel salt replenishing solution. For large-scale electroless nickel plating, it is necessary to set up automatic analysis and replenishing devices, which can extend the continuous working time (from 30h to 56h) and nickel cycle (extended from 6 weeks to 11 weeks).
Too much phosphite: discard part of the plating solution.
The loading is too low: increase the plating area to 1dm2/L.
The concentration of the stabilizer is heavy: in the pouring part, add a small amount of concentrated solution several times.
(2) The plating solution decomposes (the plating solution is churning, and nickel powder appears )
The temperature is too high or local overheating: add warm deionized water with stirring.
Most sodium hypophosphite: dilute and add other ingredients.
The pH value of the plating solution is too high: adjust the pH value to the standard value.
Mechanical impurities: remove them by filtration.
The loading volume is too high: reduce it to 1dm2/L
< p>If there is sediment on the tank wall or equipment: filter out the plating solution, remove the plating and clean (use 3% HNO3 solution).Additional liquid materials are mostly added at the operating temperature: add small amounts and multiple times under stirring.
Loss brought by stabilizer: add a small amount of stabilizer.
Catalytic substances are brought into the plating solution: strengthen cleaning before plating.
Plating peeling fragments: filter plating Liquid.
(3) Poor coating bonding or blistering
Poor pre-plating treatment: Improve the quality of the working surface. After processing, all welding spatter and welding spatter on the workpiece should be removed. Welding slag. The surface roughness of the workpiece should reach a roughness equivalent to the finishing requirements, such as the surface roughness of carbon steel workpiece Ra