JPH0244902B2 - NANJISEISEIMITSUBUHINNOHYOMENKOKASHORIHOHO - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to precision parts that constitute a magnetic circuit and require wear resistance, such as armatures and yokes used in the printing drive section of printers. The present invention relates to a surface hardening treatment method.

[Prior Art] Conventionally, precision parts that require soft magnetic properties, such as armatures and yokes of printing drive parts of printers, have been made of electromagnetic soft iron, silicon steel, etc. for the purpose of imparting rust prevention and wear resistance to their surfaces. Ni plating, Zn plating, Cr plating, Ni-P electroless plating, etc. are applied.

[Problems to be Solved by the Invention] In the conventional example described above, the surface hardness of Ni plating and Zn plating is about HV400, and there is a problem in wear resistance. Cr plating has a rating of about HV800 and is advantageous in terms of durability, but because it is electroplated, the plating coverage on parts is uneven, making it unsuitable for mass production. Ni
Even with -P plating, the abrasion resistance is low at HV400 or less, which is a problem. Note that if heat treatment is performed at around 400°C after Ni-P plating, the HV will be improved to about 800, but in that case, the original magnetic properties of the material will deteriorate, so it cannot be used.

[Means for Solving the Problems] The present invention is intended to solve the problems in the conventional examples.
First, it is annealed in vacuum for the purpose of obtaining magnetic properties and to prevent the formation of an oxide film on the surface, and then, as a pretreatment for plating, it is degreased with an organic solvent, degreased with an alkali, and pickled. Furthermore, after performing silicon oxide removal treatment using a mixed solution of acid and inhibitor, we apply cobalt-phosphorus electroless chemical plating to harden the surface with improved wear resistance without impairing the magnetic properties of the treated material. It is for processing.

[Example] First, 3% silicon steel is used as a material and processed into a predetermined part shape. Although silicon steel has excellent magnetic properties, it has an active surface and is prone to forming an oxide film (SiO2).

In the treatment method according to the present invention, as a first step,
In order to obtain the original magnetic properties of silicon steel and also to prevent the formation of an oxide film on the silicon steel surface, annealing is performed at 850°C for 1 hour in a vacuum. In this case, in a non-oxidizing atmosphere such as N2 or Ar other than a vacuum atmosphere, the surface appears to be bright, but the adhesion after the final plating finish is insufficient, and heat treatment in a vacuum atmosphere is required.

As a second step, the next process is performed as a pretreatment for electroless Co plating.

(1) Degreasing treatment is performed using organic solvents mainly to remove mineral oil. The sample is immersed in an organic solvent such as 1-1-1 trichloroethane for about 3 minutes by applying ultrasonic waves.

(2) Next, as a second degreasing treatment, the material to be treated is shaken with a mixture of alkali and a surfactant, such as a commercially available alkaline degreaser such as sodium orthosilicate, mainly for the purpose of removing animal and vegetable oils. Immerse it in the liquid for about 3 minutes while moving it.

(3) Next, mainly for the purpose of removing iron oxides,
The material to be treated is immersed in a 7% hydrochloric acid aqueous solution for about 10 to 30 seconds while rocking.

(4) Furthermore, the object to be treated is immersed for 10 to 30 seconds while rocking in a diluted mixture of acid and inhibitor, mainly containing fluorine compounds, for the purpose of removing silicon oxides. .

After performing the pre-treatments in (1) to (4) above, finally, in order to increase the durability of the object to be treated, it is immersed in a cobalt electroless plating solution using sodium diphosphite as a reducing agent. Electroless chemical Co plating, which is made by adding about 4 to 6% phosphorus to cobalt, is deposited to a thickness of about 10 to 20 μm.
If it is less than 10 μm, sufficient durability cannot be obtained, and if it exceeds 20 μm, there are problems in terms of mass production.

The treated material obtained through the above steps is Co-P.
The surface hardness of this type of chemical plating is HV400-500, which is close to conventional Ni plating, but it retains lubricity, making it suitable for precision parts that require wear resistance. .

By using the yoke of the printing mechanism of an impact-type dot printer that has been treated with the present invention,
Comparing the number of prints with a printer using Ni plating, the durability of the conventional printer was approximately 30 million characters, while the durability of the printer of the present invention was dramatically improved to approximately 200 million characters. .

[Effects of the Invention] According to the present invention, it is possible to impart not only surface hardness but also lubricity to a soft magnetic precision component while maintaining its magnetic properties, thereby improving durability.

Claims (1)

[Claims] 1 Precision parts made of soft magnetic silicon steel are annealed in a vacuum, and as pre-treatments for plating, degreasing with an organic solvent, degreasing with an alkali, pickling, and further treatment with an acid. A surface hardening treatment method for soft magnetic precision parts, comprising the steps of sequentially applying silicon oxide removal treatment using a mixed solution of and an inhibitor, and applying cobalt-phosphorus electroless chemical plating.