How to judge the quality of the sintered nd-boron

发表时间：2017-05-26

Today we're talking about magnetic material. Every time a magnetic material is said, people who may have been in this industry for many years have a thorough understanding of the various aspects of magnetic materials, and are experts. Goose, believe that some people who have just entered the industry or are interested in the industry, have heard of the magnetic material.

Today want to say is not a wide range of magnetic materials, we will point a small point, do not think that it is no meaning to small, believe that everyone is very concerned about the content of the to judge the quality of sintered ndfeb magnet? It's not a strange thing to do, it's the production process we've already talked about.

The sintering nd-nt-ti-boron magneto, as one of the important substances in promoting contemporary technology and social progress, is widely applied in the following areas:

Since 1985 in Japan, China and Europe and the United States began to industrialization at the same time, the nearly 30 years industry booming global permanent magnet materials, the magnetic can keep a record, increasing material varieties and grades. Along with the market expanding, its manufacturer also is increasing, and many customers are hard to avoid in such confusion, how to determine the pros and cons of ndfeb magnet?

The most comprehensive method of judging

The magnet performance

The magnet size

Magnetic coating

Production of raw materials

First, the protection of magnet performance comes from the control of raw material production process.

According to the requirement of the enterprise to make high-grade or medium or low gear, the raw materials according to the national standard.

The advanced quality of the production process determines the quality of the magnet. The most advanced technology is the scale casting (SC) technology, the hydrogen fragmentation (HD) technology and the JM technology.

Small capacity vacuum induction furnace (10kg, 25kg, 50kg)

Large capacity (100kg, 200kg, 600kg, 800kg) is replaced by vacuum induction furnace

SC (StripCasting) rapid casting technology

It is gradually replacing the big cast

Hydrogen crushing (HD) technology and air friction (JM)

Instead of jaw crusher, disc mill, ball mill (wet legal powder)

3, magnetic field orientation, our country is the only country adopts two-step forming technology in the world, orientation with a small vertical moulding pressure, finally USES the isostatic pressing molding, this is one of the most important characteristics of sintered ndfeb industry in our country.

Moreover, the monitoring of the quality of the production process is very important, which can be controlled by the measurement of SC film thickness and the distribution of the size distribution of JM powder. The China institute of metrology has developed various types of magnetic parameter measuring instruments for permanent magnetic materials.

Pulse field magnetometer (PFM) - test ultra high coercive permanent magnets

To tell the truth a little bit difficult, but according to the magnet parameter Br (residual magnetism), Hcb (coercive force), the Hcj (intrinsic coercive force), (BH) Max (maximum magnetic energy product) selected ndfeb brand you need.

Factory processing

Second, the size of the magnet depends on the factory's processing power.

The actual use of the nd-ti-boron permanent-magnet is a variety of shapes:

The permanent magnets of each shape have different sizes, and the process of production is difficult to achieve. The general production process is:

Produce large (large size) of the billet - - sintering and tempering - - mechanical processing (including cutting, punching) - - > grinding - > surface coating (coating) - > > detection properties, surface quality and dimensional accuracy (magnet) magnetization - - packaging - - - - > the factory.

There are three types of mechanical processing:

Cutting process: the cylinder and square column of magnets are cut into round and square pieces.

Contour machining: a magnet that processes round, square magnets into fan-shaped, watt-shaped or grooved or other complex shapes;

(3) hole processing: the round rod and the square bar magnet are processed into cylinders or cylindrical magnets. It is processed by grinding, cutting and machining of edm.

The surface of the magnetic surface of the sintered nd-nd-ferroboron is generally required to be smooth and accurate.

It is a common grinding method for the nd-nd-nd-nd-ti-borium permanent-magnet alloy.

Square: flat surface grinding, double face grinding, inner circle grinding, circular grinding, etc

Cylinder: used for grinding mill, double face grinding, etc

Watt-shaped, fan-shaped and VCM magnets: use a multi-station grinding machine

If a magnet is qualified, it is not only necessary for performance, but also the control of size tolerance directly affects its application. And the size of the security directly depend on the processing power of the factory, processing equipment as the economy and the market demand is constantly updated, the trend of more efficient equipment and industrial automation, is not only meet customers' growing demand for the product accuracy, but also save manpower and cost, make it more have market competitiveness.

Magnetic coating

Again, the quality of the magnetite coating determines the application life of the product.

Experiment, 1 cm3 of sintered ndfeb permanent magnet stay 51 days in 150 ℃ in air, will all be oxidation corrosion. It is more easily corroded in a weak acid solution. In order to make the nd-ti-boron permanent magnet durable, it will require 20-30 years of service life, and it must undergo surface anti-corrosion treatment.

At present, the sintering nd-nd-pboron permanent-magnet system is widely adopted

Plating metal

Electroplating + chemical metallization

Method of electrophoresis coating and phosphating

1, phosphating is used in some special cases: (1) in ndfeb magnet products because turnover, save the time is too long and not clear the surface of the follow-up processing method, using the phosphating is simple; (2) when the magnets need epoxy adhesives, paints, etc., the bonding force of the epoxy organic materials such as glue, paint, etc., will require good infiltration of the substrate. The process of phosphating can improve the ability to infiltrate the surface of the magnet.

Electrophoresis coating has become one of the most widely used surface treatment technologies. Because it is not only good in combination with the surface of the porous magnet, but also with the corrosion of salt resistant fog, acid and alkali resistance, the corrosion resistance is excellent. But it is less resistant to moisture and heat than spray coating.

You say so many I can't understand, simple point, throw to you two test experiment:

The experiment (also known as the PCT) was tested for corrosion resistance in wet and high temperature conditions.

Salt fog experiment - a rapid corrosion prevention experiment for sintered nd-ferroboron, which has been treated by corrosion resistant coating.