MATERIALS.CO.UK
Metals • Plastics • Rubbers • Polymers • Ceramics • Composites
Metals • Plastics • Rubbers • Polymers • Ceramics • Composites
Metals • Plastics • Rubbers • Polymers • Ceramics • Composites
materials.co.uk - metals, plastics, rubbers, polymers, ceramics, composites

MICROHARDNESS TESTER

Background

Vickers Indenter

Originally, the Vickers hardness test was developed for test loads of 1 to 120 kgf. The need for smaller indentations was subsequently recognised and a low-load "microhardness" or more correctly "microindentation" Vickers tester was developed. The shape of the Vickers indentation is geometrically similar at all test loads and therefore, the hardness value is constant over a very wide test load range, provided the test specimen is homogeneous.

Knoop Indenter

The Vickers test uses a square pyramidal indenter which is prone to crack brittle materials. Consequently, the Knoop test using an rhombic-based (diagonal ratio 7.114:1) pyramidal indenter was developed which produces longer but shallower indentations. For the same load, Knoop indentations are about 2.8 times longer than Vickers indentations. Experience with a wide range of ceramics has proven that the Knoop indentations are far less likely to crack than Vickers indentations.

Applications
  • Hardness gradients
  • Surface hardness
  • Case depth
  • Coating hardness
  • Phase hardness
  • Hardness of grains
  • Hardness at grain boundaries
  • Hardness of powders
  • Hardness of fragile materials
Leitz Miniload 2 Microhardness Tester
Leitz Miniload 2 Microhardness Tester
Specification
IndentersVickers, Knoop
Loads5 ± 0.05, 10, 15, 25, 50, 100, 200, 300, 500 g
Objectives10x, 50x
Magification100x, 500x
Stage sizeX axis 135mm, Y axis 135mm
Stage travelX axis 25mm, Y axis 25mm
Max sample height100mm approx
Standards
BS 3900-E12.1:2000,
ISO 6441-1:1999
Methods of test for paints. Determination of Knoop hardness by measurement of the indentation length using a microscope
BS 3900-E12.2:2000,
ISO 6441-2:1999
Methods of test for paints. Determination of Knoop hardness by measurement of the indentation depth
BS 5411-6:1981,
ISO 4516-1980
Methods of test for metallic and related coatings. Vickers and Knoop microhardness tests
DD ENV 843-4:1995Advanced technical ceramics. Monolithic ceramics. Mechanical properties at room temperatures. Vickers, Knoop and Rockwell superficial hardness tests
ASTM B578-87(1999)Standard Test Method for Microhardness of Electroplated Coatings
ASTM B721-91(1999)Standard Test Method for Microhardness and Case Depth of Powder Metallurgy (P/M) Parts
ASTM C730-98Standard Test Method for Knoop Indentation Hardness of Glass
ASTM C849-88(1999) Standard Test Method for Knoop Indentation Hardness of Ceramic Whitewares
ASTM C1326-99Standard Test Method for Knoop Indentation Hardness of Advanced Ceramics
ASTM C1327-99Standard Test Method for Vickers Indentation Hardness of Advanced Ceramics
ASTM E384-99e1Standard Test Method for Microindentation Hardness of Materials

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