|
Originally, the Vickers hardness test was developed for
test loads of 1 to 120 kgf. The need for smaller
indentations was subsequently recognized 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. |
| 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. |
-
Hardness gradients
-
Surface hardness
- Case
depth
-
Coating hardness
- Phase
hardness
-
Hardness of grains
-
Hardness at grain boundaries
-
Hardness of powders
-
Hardness of fragile materials
|
| Indenters |
Vickers, Knoop |
| Loads |
5 ± 0.05, 10, 15, 25, 50, 100, 200, 300, 500 g |
| Objectives |
10x, 50x |
| Magification |
100x, 500x |
| Stage size |
X axis 135mm, Y axis 135mm |
| Stage travel |
X axis 25mm, Y axis 25mm |
| Max sample height |
100mm approx |
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
843-4:1995 |
Advanced
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
C730-98 |
Standard
Test Method for Knoop Indentation Hardness of Glass |
| ASTM
C849-88(1999) |
Standard
Test Method for Knoop Indentation Hardness of Ceramic
Whitewares |
| ASTM
C1326-99 |
Standard
Test Method for Knoop Indentation Hardness of Advanced
Ceramics |
| ASTM
C1327-99 |
Standard
Test Method for Vickers Indentation Hardness of Advanced
Ceramics |
| ASTM
E384-99e1 |
Standard
Test Method for Microindentation Hardness of Materials |
