Rapid nondestructive testing method for permanent magnet material-based sub-quality product with poor room-temperature and high-temperature performances

Abstract

The invention, which belongs to the field of the magnetic functional material nondestructive testing technology, relates to a rapid nondestructive testing method for a permanent magnet material-based sub-quality product with poor room-temperature and high-temperature performances. The method comprises the following steps that: after saturation magnetizing on a permanent magnet material, the magnetized permanent magnet material is heated to a work temperature of the magnet, a demagnetizing field with the strength of 80% to 100% Hk is applied to the magnet for demagnetization, and cooling is carried out; and a room-temperature open-circuit flux of the magnet after the demagnetization is detected and the sample with the measurement value lower than a set testing standard is a sub-quality product. According to the invention, samples with unqualified indicators like residual magnetism Br, an intrinsic coercive force Hcj, a magnetic induction coercive force Hcb, a magnetic energy product (BH)max, and a critical magnetic field strength and the like can be detected comprehensively; and a product with a poor room temperature performance and a product with a poor high temperature performance can be detected. High-temperature demagnetization can be carried out on multiple or even hundreds of samples simultaneously; the measurement of the open-circuit flux can be carried out conveniently; and the method has the characteristics of accuracy, simpleness, rapidity, and low cost and is suitable for application to large-scale production.

Description

technical field [0001] The invention relates to a method for realizing rapid non-destructive detection of permanent magnet room temperature and high-temperature performance unqualified products by measuring the open-circuit magnetic flux after high-temperature demagnetization, and belongs to the technical field of non-destructive detection of permanent magnet materials. Background technique [0002] Permanent magnet materials are widely used in electronic information, electromechanical, instrumentation and medical equipment and other fields, especially rare earth permanent magnets represented by NdFeB permanent magnet materials, which have high magnetic properties and are used in hard disk drives (HDD), motors and It has an irreplaceable position in high-tech products such as nuclear magnetic resonance instruments. However, due to the influence of the preparation process, the inhomogeneity of the properties of permanent magnet materials exists widely, especially the inhomoge...

AI Technical Summary

Problems solved by technology

However, due to the influence of the preparation process, the inhomogeneity of the properties of permanent magnet materials exists widely, especially the inhomogeneity of high-temperature magnetic properties is more prominent, which often leads to the loss of magnetism in the use of materials, resulting in poor performance of motors and other products. drop, or even scrap

[0003] However, existing technical means are difficult to carry out piece-by-piece non-destructive testing of permanent magnet materials in large-scale production

At present, in the field of permanent magnet material detection, there are mainly two problems: 1) Gaussmeter and fluxmeter commonly used in simple measurement are convenient and fast, but the accuracy is not enough

Moreover, these conventional detection methods generally only detect the performance of the sample at room temperature. However, practice has proved that the permanent magnet sample with room temperature performance does not guarantee its high temperature performance.

2) The normal temperature and high temperature performance of the sample can be tested by using the permanent magnet measurement system, but this method is not convenient enough. In mass production, if the sample is tested one by one, the workload is very huge and it is difficult to achieve

Using conventional Gauss meter and fluxmeter measurement methods can easily detect samples with unqualified remanence and magnetic energy product, but unqualified coercive force, especially the room temperature coercive force is qualified but the high temperature is unqualified, especially the high temperature coercivity The unqualified force inflection point is a major difficulty in rapid and nondestructive testing

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