阅读说明：本技术 一种基于超声波的涂层厚度测量方法 (Coating thickness measuring method based on ultrasonic waves ) 是由 庞瑞强 张晓丽 郭刚虎 武子洁 马城 杨东星 董平 赵淑荟 陈辰 单佳鑫 赵平平 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种基于超声波的涂层厚度测量方法,首先在被测涂层的表面设置一个辅助水层,所述辅助水层的高度大于超声波在水传播速度与和涂层中传播速度之比；然后将所述超声波探测仪的探测头安装在所述辅助水层的上方,使所述超声波探测仪的探测头与所述辅助水层的水平面齐平；最后通过所述超声波探测仪后得到超声波波形图,记录超声波波形图中第一个特征反射波波峰所在时刻t1和第二个特征反射波波峰所在时刻t2；得出待测涂层的厚度。本发明的涂层厚度测量方法,可对较薄涂层的厚度值进行准确测量。(The invention discloses a coating thickness measuring method based on ultrasonic waves, which comprises the steps of firstly arranging an auxiliary water layer on the surface of a measured coating, wherein the height of the auxiliary water layer is greater than the ratio of the propagation speed of the ultrasonic waves in water to the propagation speed of the ultrasonic waves in the coating; then mounting a probe of the ultrasonic detector above the auxiliary water layer, and enabling the probe of the ultrasonic detector to be flush with the horizontal plane of the auxiliary water layer; finally, an ultrasonic wave oscillogram is obtained through the ultrasonic wave detector, and the time t1 when the first characteristic reflected wave peak is located and the time t2 when the second characteristic reflected wave peak is located in the ultrasonic wave oscillogram are recorded; and obtaining the thickness of the coating to be measured. The coating thickness measuring method can accurately measure the thickness value of a thinner coating.)

1. A coating thickness measuring method based on ultrasonic waves is characterized by comprising the following specific testing steps:

1) arranging an auxiliary water layer on the surface of the measured coating, wherein the height of the auxiliary water layer is greater than the ratio of the propagation speed of the ultrasonic waves in water to the propagation speed of the ultrasonic waves in the coating;

2) installing a probe of the ultrasonic detector above the auxiliary water layer, and enabling the probe of the ultrasonic detector to be flush with the horizontal plane of the auxiliary water layer;

3) turning on the ultrasonic detector to obtain an ultrasonic oscillogram, and recording the time t1 when the first characteristic reflected wave peak is located and the time t2 when the second characteristic reflected wave peak is located in the ultrasonic oscillogram; obtaining the thickness of the coating to be measured by the formula I;

c × 1/2(t2-t1) (one)

In the formula, S is the thickness of the coating to be measured; and c is the propagation speed of the ultrasonic wave in the coating to be measured.

Technical Field

The invention relates to a coating thickness measuring method based on ultrasonic waves, and belongs to the field of coating thickness measurement.

Background

In order to make a workpiece more corrosion resistant or resistant to certain environmental factors, a coating with a certain thickness is often applied or sprayed on the surface of the workpiece to isolate the workpiece from the environment in contact with the workpiece. The thickness of the applied or sprayed coating is a key indicator and often requires non-destructive measurement control. At present, the nondestructive measurement method mainly adopts an ultrasonic method, the ultrasonic method utilizes the characteristic of ultrasonic pulse reflection, when a beam of ultrasonic wave with fixed frequency passes through an interface, the ultrasonic wave is reflected, and the propagation speed of the ultrasonic wave in a specific medium is fixed, so that the thickness of the measured medium can be determined by accurately measuring the propagation time of the ultrasonic wave reflected on the medium interface. However, when the ultrasonic instrument records the echo, the ultrasonic signal initially sent by the probe head is firstly recorded, namely, clutter appears at the initial wave position of an ultrasonic wave waveform diagram, so that a measuring blind area is formed. When the thickness of the coating to be measured is thin, the echo time generated by the ultrasonic wave passing through the coating and the workpiece substrate interface is short, the characteristic reflected wave formed by the echo in the ultrasonic wave oscillogram can be overlapped with the clutter, the echo time generated by the coating and the workpiece substrate interface cannot be clearly distinguished, and therefore the accurate thickness of the thin coating cannot be determined.

Disclosure of Invention

The invention aims to solve the problem that a traditional ultrasonic method cannot accurately measure a coating with a relatively thin thickness, and provides a coating thickness measuring method based on ultrasonic waves.

The purpose of the invention is realized by the following technical scheme:

the invention relates to a coating thickness measuring method based on ultrasonic waves, which comprises the following specific testing steps:

1) arranging an auxiliary water layer on the surface of the measured coating, wherein the height of the auxiliary water layer is greater than the ratio of the propagation speed of the ultrasonic waves in water to the propagation speed of the ultrasonic waves in the coating;

2) installing a probe of the ultrasonic detector above the auxiliary water layer, and enabling the probe of the ultrasonic detector to be flush with the horizontal plane of the auxiliary water layer;

3) turning on the ultrasonic detector to obtain an ultrasonic oscillogram, and recording the time t1 when the first characteristic reflected wave peak is located and the time t2 when the second characteristic reflected wave peak is located in the ultrasonic oscillogram; obtaining the thickness of the coating to be measured by the formula I;

c × 1/2(t2-t1) (one)

In the formula, S is the thickness of the coating to be measured; and c is the propagation speed of the ultrasonic wave in the coating to be measured.

Principle of operation

The coating thickness measuring device adopts an ultrasonic testing principle, and an auxiliary water layer is arranged on the surface of a measured coating; after passing through a water layer, the ultrasonic waves are partially reflected on an interface between the water layer and the coating to be detected, and a first interface echo is generated; after the residual ultrasonic waves penetrate through the thickness of the coating and reach the interface between the coating and the workpiece substrate, partial reflection occurs again to generate a second interface echo; and the time difference between two interface echoes is the time for the ultrasonic wave to propagate back and forth once in the coating, and the thickness of the coating to be measured can be obtained according to the specific propagation speed of the ultrasonic wave in the coating.

Advantageous effects

The method for measuring the thickness of the coating is simple, convenient and quick to operate, has no limitation of the thickness of the coating, and can accurately measure the thickness value of a thinner coating.

Drawings

FIG. 1 is a schematic view of the structure of an apparatus used in the measurement method of the present invention;

FIG. 2 is a schematic diagram of waveforms obtained during testing by the measurement method of the present invention;

in the figure, 1-probe head; 2-auxiliary water bag; 3-ultrasonic wave host computer; 4-coating to be detected;

Detailed Description

The invention is further described with reference to the following figures and examples.

Examples

The invention relates to a coating thickness measuring method based on ultrasonic waves, which adopts equipment as shown in figure 1 and comprises an ultrasonic detector and an auxiliary water bag 2;

the auxiliary water bag 2 is a cylindrical supporting piece with an opening at the lower end, a probe connecting hole is formed in a bottom plate at the upper end of the auxiliary water bag 2, and the distance from the bottom plate at the upper end of the auxiliary water bag 2 to the opening end is larger than the ratio of the propagation speed of ultrasonic waves in water to the propagation speed of ultrasonic waves in the coating 4 to be detected;

the ultrasonic detector comprises an ultrasonic main machine 3 and a probe head 1 led out from the ultrasonic main machine 3;

the specific testing steps are as follows:

1) placing the auxiliary water bag 2 above the coating 4 to be tested in a close fit manner, and filling the auxiliary water bag 2 with water;

2) installing a probe 1 of the ultrasonic detector in a probe 1 connecting hole of a bottom plate at the upper end of the auxiliary water sac 2, so that the probe 1 of the ultrasonic detector is flush with the bottom plate at the upper end of the auxiliary water sac 2;

3) turning on the ultrasonic detector to obtain an ultrasonic waveform diagram, wherein the ultrasonic waveform diagram is shown in fig. 2, and the time t1 when the first characteristic reflected wave peak is located and the time t2 when the second characteristic reflected wave peak is located in the ultrasonic waveform diagram are recorded; the thickness of the coating 4 to be measured can be obtained by the formula (I);

c × 1/2(t2-t1) (one)

In the formula, S is the thickness of the coating 4 to be measured; c is the propagation speed of the ultrasonic waves in the coating 4 to be measured.