“Qness”努氏硬度试验计系列使努氏硬度测试达到了一个全新的水平。我们的最新一代的高端型号结合了短周期时间和最大化的精度。杰出的功能如8位转塔、全面的软件以及通过Qconnct的连接,使该努氏硬度计系列成为市场上极具创新产品的最佳选择。
1939年,Knoop, Emerson和Peters开发了努氏硬度测试方法,以便在薄层样品中得到更可靠的硬度测试结果。基本上,它与维氏硬度测试非常相似。在这里,使用一个纵向边缘角为172.3°,横向边缘角为130°的菱形金刚石锥体作为压头。该压头依次用特定的测试力垂直按压入到工件表面。卸载后,测量产生的压痕,只测量长对角线d1。
然后计算试验力和压痕投影面积的商作为努氏硬度。
努氏测试方法仅适用于小力值(不超过10N)和显微硬度范围内。
根据DIN EN ISO 6508-1标准,努氏硬度测试结果按下面形式表示 :
700 HK 0.2 / 20 ⇒ 努氏硬度值
700 HK 0.2 / 20 ⇒ 努氏硬度缩写
A Knoop hardness tester is used to measure the hardness of brittle materials or thin sections, such as ceramics, glass, and coatings. It is particularly useful for materials that might crack or deform under heavier loads used in other hardness tests.
The Knoop test involves pressing a rhombic-shaped diamond indenter into the material's surface under a specific load. The length of the long diagonal of the indentation is measured, and the Knoop hardness number (KHN) is calculated based on the applied load and the indentation size.
The Knoop test is advantageous for its ability to test very small or thin samples and its suitability for brittle materials. It requires minimal sample preparation and provides precise hardness values with minimal risk of cracking the specimen.
Both Knoop and Vickers tests use diamond indenters, but the Knoop indenter is elongated, producing an indentation with a longer diagonal, which is measured. Knoop is preferred for anisotropic materials and thin films, while Vickers is better for isotropic materials and thicker samples.
Accuracy can be influenced by the surface preparation of the specimen, the precision of the indentation measurement, and the alignment of the indenter. Proper calibration and maintenance of the testing equipment are also crucial for obtaining accurate results.