comparative
hardness values
Vickers
- HV 1 |
Brinell
- HB 2 |
Rockwell
- HRC 3 |
320 |
304 |
32,2 |
340 |
323 |
34,4 |
360 |
342 |
36,6 |
380 |
361 |
38,8 |
400 |
380 |
40,8 |
430 |
409 |
43,6 |
460 |
437 |
46,1 |
490 |
- |
48,4 |
500 |
- |
49,1 |
550 |
- |
52,5 |
600 |
- |
55,2 |
650 |
- |
57,8 |
700 |
- |
60,4 |
800 |
- |
65,7 |
900 |
- |
70,9 |
1000 |
- |
76,3 |
1 = for hard
and soft materials
2 = for all
materialswhich are softer than hardened steel
1 = for
hard materials, e.g. hardened steel
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Electroless
nickel - hardness of deposited layers
4 kinds of
the hardness exist:
Vickers
(HV), Rockwell (HRC),
Brinell
(HB), Knoop
(HK) |
Particularly
to the determination of the hardness of Ni-P-layers
the Vickers hardness is very common and most extensive in application.
Measurement
principle: A diamond pyramid penetrates under defined conditions
into the coat. The mathematical evaluation is made by the penetration
depth of the pyramid diagonals. For avoidance of wrong measurements the
minimum layer thickness must amount to approx. 20 µm since the
penetration depth of the pyramid needs up to 15µms. Thinner layers are
measured either in transverse cross section by 90° or but based on an accompanying
inspection piece parallel in a en bath.
En layers are in the freshly
deposited condition 3 time harder as
galvanically deposited nickel layers - approx. 500 HV to 150 HV.
By differentiated
heat treatments - partial under inert gas - and in dependence
of the phosphorus content in the layer can be achieved hardness increases up to 1200
HV.
Under
adherence to consistent working conditions one obtains positive results
in this connection to friction and wear protection rates, which are
recognizable in principle over abrasion test.
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