Composite chemical nickel and phosphor plating method

Abstract

The invention relates to a composite chemical nickel and phosphor plating method, characterized by comprising the following steps: 1) the pH value of the chemical nickel and phosphor plating solution containing nickel sulfate with the concentration being 26 to 30 g / l, sodium hypophosphite with the concentration being 23 to 27 g / l, sodium citrate with the concentration being 38 to 42 g / l and sodium acetate with the concentration being 23 to 27 g / l is adjusted to be 9 to 10, neodymium(III) sulfate octahydrate is mixed with the chemical nickel and phosphor plating solution uniformly at the addition amount is 0.4 to 0.8 g / l, the above solution is plated on the pretreated neodymium iron boron magnet under the effect of the ultrasonic wave for 10 to 60 minutes to obtain a nickel and phosphor plating layer with the crystal grain size of 5 to 8 nm; 2) the pH value of the chemical nickel and phosphor plating solution containing nickel sulfate with the concentration being 22 to 26 g / l, sodium hypophosphite with the concentration being 28 to 32 g / l, sodium citrate with the concentration being 43 to 47 g / l and sodium acetate with the concentration being 28 to 32 g / l is adjusted to be 4.2 to 5.6, the plated neodymium iron boron magnet in the step(1) is placed into the chemical nickel and phosphor plating solution in the step(2) for plating for 30 to 120 minutes, the amorphous nickel and phosphor plating layer is obtained. Compared with the prior art, the plating layer has high adhesion and good corrosion resistance, the thickness of the plating layer can be reduced and the loss of the magnetic property can be lowered.

Description

technical field

[0001] The invention relates to the field of material surface protection, in particular to a composite electroless nickel-phosphorus plating method. Background technique

[0002] Sintered NdFeB magnet is a rare earth permanent magnet material developed in the 1980s. Its appearance and development have greatly promoted industrial progress, and it has been more and more widely used in many fields of national economy such as electronic information and aerospace. Due to the structure and chemical characteristics of sintered NdFeB, its corrosion resistance is poor, and its surface must be protected.

[0003] At present, the surface protection of NdFeB usually adopts electroplating process, which has problems such as insufficient protection level, poor protection efficiency for deep hole parts and special-shaped workpieces, and high environmental protection treatment costs. At the same time, international environmental protection standards for electroplating produ...