The increasingly stringent demands being placed on surface treatment technology has necessitated measuring processes and devices that meet the new requirements. The Helmut Fischer Group have researched and developed the micro hardness measuring systems HM2000 and Picoindentor HM500 to offer laboratories and manufacturing industry involved in miniaturisation some of the most flexible and precise hardness measuring systems on the market.
ISO 14677-1 specifies the method of instrumented indentation test for the determination of hardness and other materials parameters for the three ranges: macro, a test force between 2 N and 30 kN; micro, a test force less than 2 N; indentation depth greater than 0.2 m; nano, an indentation depth equal to or less than 0.2 m. The Fischer systems exceed the ISO requirements and in doing so, offer first class precision hard to match in its price range.
Systems With Real Scope and Flexibility
The HM2000 Micro Hardness system measures Martens Hardness, which has the advantage of being free of subjective influences such as the optical measurement of the indentation diagonal. A clear advantage, but Fischer recognise that needs vary and consequently the flexibility of the HM2000 allows for hardness measurement using Berkovich or a spherical indenter of diameter 0.4mm. In addition, a simple measurement according to Vickers is also possible by the direct measurement of the indentation on the video screen.
Indentation Load Capacity
Probably one of the most significant developments has been the capacity of the HM2000 to handle indentation loads of up to 2N. This is twice the previous maximum test load, which gives it first class precision and reliability and clear-cut measurement results on coatings with rough surfaces and coarse material textures.
Coating Quality Control
New applications cover quality control of hard material coatings on cutting and forming tools, galvanic coatings such as deposited nickel coatings, gold coatings on contacts for electrical components, paint and lacquer in the automotive industry and synthetic foils.
Measuring the Thinnest Nanometer Coatings
The Picoindenter HM500 has been developed specifically to measure the thinnest nanometer coatings. Its flexibility extends to material characteristic analysis, such as the elastic indentation modulus, simply by evaluating the unload plot.
Coated spectacle lenses are just one example of hard coatings on soft substrates, which need special measurement techniques. The determination of the technological properties of such coatings is essential for their optimisation and the Picoindentor micro hardness testing system has evolved as the answer, offering enormous scope.
Further applications include ultra thin DLC coatings, dirt-repellent coatings, PC hard disk/CD coatings, very thin lacquer coatings, ion-implanted surfaces, nanocoatings for sensors, implants/medical technology, matrix effects in alloys, biological materials and ceramic materials
Precision and Versatility of Measurements
The specified test load is built up with high precision. The measurement of the indentation depth is carried out with a resolution in the picometer or nanometer range.
The extremely sensitive touchdown of the indenter allows for the exact determination of the zero point. This is significantly below the measurement uncertainty of <1%, prescribed by the standards. The tip roundness of the indenter is determined using a reference measurement, which is taken into account in the results. The microhardness determination is computer controlled and as such is free of any subjective influences, to include the operator.
In one single measurement, the user obtains information about the hardness of the surface, the hardness pattern within boundary layers near the surface, the elastic and plastic properties and the creep properties of the material. Additional interesting characteristic qualities of the material can be computed from the recorded measurement plot, such as modulus of indentation and the elastic plastic energy portions.
Micro hardness systems have previously been considered a considerable investment and some of the top end systems may indeed be out of the range of the average laboratory or manufacturing organisation. At the other end of the scale are the simple micro hardness instruments, which dent the material and leave you to measure the diagonal. Fischer’s mid-range systems have found themselves in perfect balance, offering versatility of application, minimal destructiveness, above standard results presentation and useability, all at an affordable cost.