Finding Similarities Between Tips and Life

Arts & Entertainment

Microhardness Testing – The Difference between Vickers and Knoop Hardness Tests Hardness test systems use an indenter probe which is displaced into a surface under a precise load. The indentation normally comes with a defined dwell time. Traditional mechanical testing requires the measurement of the indentation’s size or depth in order to determine hardness. Macrohardness and microhardness are the two ranges of hardness testing. Macrohardness involves testing with over 1 kg or some 10 Newton (N) in applied load. Microhardness testing that has applied loads not reaching 10 N, is often reserved plated surfaces, thin films, smaller samples or thin specimens. Vickers and Knoop hardness tests are the two most common microhardness techniques used today. For more exact and repeatable results, microhardness testing has to be responsible for the effects of sample preparation, size and environment. Samples have to fit in the sample stage and be in a position that is perpendicular to the indenter tip. A particularly rough surface can diminish the accuracy of indentation data; it is best to use a tested and proven procedure for polishing samples. It is important that the microhardness tester be isolated from vibrations. If samples vary in grain size or have several phases, statistical data is a must. Vickers Hardness
Tests: 10 Mistakes that Most People Make
The Vickers hardness test makes use of a Vickers indenter that is pressed against a surface to a pre-determined force maintained usually for 10 seconds. Once the indentation is completed, the resulting indent is examined optically to determine the lengths of the diagonals, which is important in determining the size of the impression.
Finding Similarities Between Tips and Life
There is, in the lower range of the applied load, some degree of operator bias that must be expected using this method. The length of indentation diagonals, as per ASTM E384-11, must be more than 17 microns in length. This test is not valid for coated samples with coating thicknesses below 60 microns. For several kinds of samples, the contact depth is different from the displacement depth since the surrounding material becomes elastically deflected during the indentation process. In addition, this effect also has an impact on accuracy and precision for microhardness data. Knoop Hardness Another microhardness technique is known as the Knoop hardness test, which is similar to the Vickers hardness test. The procedure involves a Knoop indenter pushing into a surface in order to measure hardness. However, being more elongated or rectangular, the Knoop indenter is shaped uniquely from a Vickers indenter for microhardness, or a Berkovich indenter for nanoindentation. The Knoop hardness test method is often used for the microhardness testing of lighter loads, and requires meticulous sample preparation. Knoop hardness testing is used on samples that need indentations to be close together or on the sample’s edge, with both benefitting from the unique probe shape. A particular load is applied for a pre-defined dwell time. The Knoop test method only makes use of the long axis, in contrast to the Vickers hardness method. The indentation measurements that result from this are then converted to a Knoop hardness number with the use of a chart.