介绍了超声波接触阻抗（UCI）硬度试验的原理以及UCI硬度试验设备的结构、操作方法和主要特点。应用UCI硬度计对某渗碳淬火滚轮零件外圆面进行了UCI硬度试验，对影响试验结果的各主要不确定度来源进行了分析，并对试验结果的测量不确定度进行了评定。结果表明：UCI法测得该滚轮零件的硬度H_UCI=（63.2±1.6） HRC，包含因子k=2；UCI硬度试验最主要的测量不确定度来源为硬度转换引入的不确定度以及测量重复性误差引入的不确定度；在实际检测时最好选择直接输出维氏硬度，尽量减少由于硬度转换带来的不确定度，同时建议配备专门的测量工装或者辅助工具，帮助稳定测试过程，减少测量的重复性误差。

The principle, structure of equipment, operating method and main characteristics of ultrasonic contact impedance (UCI) hardness test were introduced. The UCI hardness tester was used to determine the excircle surface hardness of a carburized and quenched roller part. The main sources of measurement uncertainty affecting the test results were analyzed and the measurement uncertainty of the testing results was evaluated. The results show that the UCI hardness of the roller part was H_UCI=(63.2±1.6) HRC when the coverage factor k=2. The main sources of measurement uncertainty for UCI hardness test were the harness conversion and the repeatability error of measurement. In practical test, Vickers hardness was recommended as the output hardness in order to minimize the uncertainty of harness conversion. It was also recommended to use special tools or assistive devices to stabilize the test process and reduce repeatability error of measurement.