1. A method for measuring the thickness of an iron and steel oxide film is characterized by comprising the following steps: the measuring method comprises the following steps: cleaning the surface, dripping membrane-removing liquid, dissolving an oxide membrane, wiping off residual liquid to form a round spot, wiping the round spot clean by absolute ethyl alcohol, carrying out contact measurement on the inside and the outside of the round spot by a probe of a profilometer, forming a profile graph, measuring the height difference and forming an oxide membrane thickness test value; the method specifically comprises the following steps: wiping clean degreasing and oilless on the surface of an oxide film layer of a steel part to be tested by using an organic solvent, dripping a drop of special stripping liquid on the surface, staying for 3-8 minutes to completely dissolve and remove the oxide film, wiping the drop by using absorbent cotton, cotton cloth or test paper until no residual liquid exists on the surface of the steel part, dipping anhydrous ethanol to wipe the test surface clean, forming gray round spots at the position of the drop subjected to surface stripping, having obvious boundary and having obvious difference with the appearance color of the surface of a normal oxide film; the method comprises the steps of placing a test piece in the middle of a test platform of a profiler, pushing a gray circular spot part to the lower side of a probe, positioning the probe 1-2mm above the gray circular spot, setting a measurement coordinate at the left side of the circular spot, setting a left and right test displacement outside the circular spot to be not less than 5mm, contacting the probe with a workpiece, starting profile measurement, starting measurement by the probe from 5mm away from the left side of the circular spot, stopping measurement after the probe passes through the circular spot and 5mm away from the right side of the circular spot, forming a profile graph on a display, enabling the circular spot of a liquid drop to have an obvious height difference with the surface of a normal oxide film, enabling the circular spot of the liquid drop to be lower than the normal surface, measuring the height difference by the profiler, enabling the measured height difference to be the thickness of the oxide film, and enabling the measurement accuracy to be 0.01 micrometer.

2. The method for measuring the thickness of the steel oxide film according to claim 1, wherein the method comprises the following steps: the organic solvent is absolute ethyl alcohol or gasoline or chlorinated hydrocarbon.

3. The method for measuring the thickness of the steel oxide film according to claim 1, wherein the method comprises the following steps: the demolding liquid is a 4% urotropine-hydrochloric acid aqueous solution.

Background

Several methods are commonly used for coating thickness measurement: microscopy, coulometry, X-ray, magnetic induction measurement, eddy current, micrometer. Wherein the thickness measurement by a microscope (GB 6462-; however, the measurement needs to be carried out by preparing a sample, selecting a cross section perpendicular to the surface of the covering layer, then cutting and preparing the cross section, and sampling, inlaying, grinding, polishing, etching and other processes are needed.

Because the thickness of the steel oxide film is generally within 2 μm, the film is too thin, the above methods can not accurately measure, and at present, the standard of the measuring method of the thickness of the steel oxide film is not available in China; the film weight measurement method is generally adopted internationally, in DIN 50938 requirements and test methods for black oxide coatings on Steel parts, film weight test method: weighing a dried test piece on an analytical balance, immersing the test piece into a film weight test solution, removing an oxide film, cleaning, drying and weighing, and calculating the weight of a film layer in unit area according to the mass difference before and after film removal; this method, however, cannot accurately and intuitively measure the oxide film thickness.

The measuring method of the cross section thickness microscope needs to destroy, cut and prepare a sample for a sample piece, and needs to inlay, polish and etch, has high requirements for the quality of the cross section, complex operation process and long time, can not detect quickly, has thinner steel oxide film which is generally within 2 microns, has unobvious coating after etching, is not easy to observe by a microscope, and can not measure the thickness of the steel oxide film accurately.

According to the oxide film weight measurement method adopted internationally, a test piece and an untreated blank test piece are required, a test solution is prepared firstly, the test piece is immersed into the test solution for film stripping treatment, the test piece is required to be cleaned, dried and weighed by an analytical balance before and after film stripping, the surface area of the test piece is calculated by measuring the size of the test piece, and the oxide film weight is calculated according to a formula; if the size of the test piece or the weight of the film exceeds the weighing range or the measuring precision of the analytical balance (the weight of the steel oxide film is generally not more than 10 g/m)²) Or the calculation error of the area of the irregular part is large, the film weight of the oxide film cannot be accurately tested easily, and at the moment, a special test piece is required to carry out oxidation treatment for testing, so that the operation is complex. And the method can not intuitively and accurately measure the thickness of the steel oxide film.

Disclosure of Invention

The invention aims to provide a method for measuring the thickness of an iron and steel oxide film, which can solve the problem of intuitively and quickly measuring the thickness of the iron and steel oxide film under the condition of not damaging iron and steel parts.

The invention adopts the following technical scheme for achieving the purpose:

a method for measuring the thickness of an iron and steel oxide film comprises the following steps: cleaning the surface, dripping membrane-removing liquid, dissolving an oxide membrane, wiping off residual liquid to form a round spot, wiping the round spot clean by absolute ethyl alcohol, carrying out contact measurement on the inside and the outside of the round spot by a probe of a profilometer, forming a profile graph, measuring the height difference and forming an oxide membrane thickness test value; the method specifically comprises the following steps: wiping clean degreasing and oilless on the surface of an oxide film layer of a steel part to be tested by using an organic solvent, dripping a drop of special stripping liquid on the surface, staying for 3-8 minutes to completely dissolve and remove the oxide film, wiping the drop by using absorbent cotton, cotton cloth or test paper until no residual liquid exists on the surface of the steel part, dipping anhydrous ethanol to wipe the test surface clean, forming gray round spots at the position of the drop subjected to surface stripping, having obvious boundary and having obvious difference with the appearance color of the surface of a normal oxide film; the method comprises the steps of placing a test piece in the middle of a test platform of a profiler, pushing a gray circular spot part to the lower side of a probe, positioning the probe 1-2mm above the gray circular spot, setting a measurement coordinate at the left side of the circular spot, setting a left and right test displacement outside the circular spot to be not less than 5mm, contacting the probe with a workpiece, starting profile measurement, starting measurement by the probe from 5mm away from the left side of the circular spot, stopping measurement after the probe passes through the circular spot and 5mm away from the right side of the circular spot, forming a profile graph on a display, enabling the circular spot of a liquid drop to have an obvious height difference with the surface of a normal oxide film, enabling the circular spot of the liquid drop to be lower than the normal surface, measuring the height difference by the profiler, enabling the measured height difference to be the thickness of the oxide film, and enabling the measurement accuracy to be 0.01 micrometer.

The organic solvent is absolute ethyl alcohol or gasoline or chlorinated hydrocarbon.

The demolding liquid is a 4% urotropine-hydrochloric acid aqueous solution.

According to the method for measuring the thickness of the steel oxide film, the technical scheme is adopted, the steel part is directly measured in a positioning mode, a test piece is not required to be damaged by cutting and sample preparation, the test operation is simple, the efficiency is high, the thickness measurement result of the steel oxide film is accurate, the precision is high, the image is visual, and the problem that the thickness of the steel oxide film cannot be accurately and directly measured is solved.

Drawings

FIG. 1 is a graph of a profile formed by the measurement of the present invention.

Detailed Description

The invention is described in connection with the accompanying drawings and the specific embodiments:

referring to fig. 1, a method for measuring the thickness of an oxide film of steel comprises the following steps: cleaning the surface, dripping membrane-removing liquid, dissolving an oxide membrane, wiping off residual liquid to form a round spot, wiping the round spot clean by absolute ethyl alcohol, carrying out contact measurement on the inside and the outside of the round spot by a probe of a profilometer, forming a profile graph, measuring the height difference and forming an oxide membrane thickness test value; the method specifically comprises the following steps: after the bearing part is oxidized, a test piece is taken, absolute ethyl alcohol is dipped in cotton cloth to wipe the surface of an oxidation film, the absolute ethyl alcohol on the surface is wiped to be volatilized and dried, then membrane removing liquid is dripped on the surface, the liquid drops stay for 4 minutes, the oxidation film is completely dissolved, residual liquid is wiped off by the cotton cloth, the test surface is wiped cleanly by dipping the absolute ethyl alcohol in the cotton cloth, gray circular spots are formed at the membrane removing liquid drop position on the surface, the boundary is obvious, the test piece is placed in the middle of a test platform of a profiler, a probe is positioned above the gray circular spots, measurement coordinates are set, the measurement displacement of the probe is 10mm through the gray circular spots and the left and right measurement displacement outside the circular spots, contact measurement is carried out on the inside and the outside of the circular spots by using the profiler probe to form a profile figure, the displacement position of the circular spots in the profile figure is obviously lower than the outside the circular spots, an obvious height difference is the thickness of the oxidation film, and the profile profiler directly measures the height difference, the average value of the height difference of the test is the thickness of the oxide film, and the measurement accuracy can reach 0.01 um.

The organic solvent is absolute ethyl alcohol or gasoline or chlorinated hydrocarbon.

The demolding liquid is a 4% urotropine-hydrochloric acid aqueous solution.

The profile graph formed by measurement is shown in figure 1, the low concave platform is a demoulding circular spot, the high platforms at two sides are parts with oxidation films outside the circular spot, the steps are obvious, the height difference profilometer directly measures to give an average value, the average value of the film thickness of the measurement result of the graph is 1.5um, and the precision can reach 0.01 um.