Chemical elements
  Iron
    History of Iron
    Mineralogy
    Isotopes
    Energy
    Production
    Application
    Physical Properties
      Allotropy
      Occlusion of Gases
      Absorption of Nascent Hydrogen
      Permeability to Gases
      Passivity of Iron
      Iron Powder
      Iron sponge
      Iron amalgam
      Colloidal Iron
      Pyrophoric Iron
      Catalyst
      Iron Ions
      Atomic Weight
    Chemical Properties
    Corrosion
    Iron Salts
    PDB 101m-1aeb
    PDB 1aed-1awd
    PDB 1awp-1beq
    PDB 1bes-1c53
    PDB 1c6o-1ci6
    PDB 1cie-1cry
    PDB 1csu-1dfx
    PDB 1dgb-1dry
    PDB 1ds1-1e08
    PDB 1e0z-1ehj
    PDB 1ehk-1f5o
    PDB 1f5p-1fnp
    PDB 1fnq-1fzi
    PDB 1g08-1gnl
    PDB 1gnt-1h43
    PDB 1h44-1hdb
    PDB 1hds-1i5u
    PDB 1i6d-1iwh
    PDB 1iwi-1jgx
    PDB 1jgy-1k2o
    PDB 1k2r-1kw6
    PDB 1kw8-1lj0
    PDB 1lj1-1m2m
    PDB 1m34-1mko
    PDB 1mkq-1mun
    PDB 1muy-1n9x
    PDB 1naz-1nx4
    PDB 1nx7-1ofe
    PDB 1off-1p3t
    PDB 1p3u-1pmb
    PDB 1po3-1qmq
    PDB 1qn0-1ra0
    PDB 1ra5-1rxg
    PDB 1ry5-1smi
    PDB 1smj-1t71
    PDB 1t85-1u8v
    PDB 1u9m-1uyu
    PDB 1uzr-1vxf
    PDB 1vxg-1wri
    PDB 1wtf-1xlq
    PDB 1xm8-1y4r
    PDB 1y4t-1ygd
    PDB 1yge-1z01
    PDB 1z02-2a9e
    PDB 2aa1-2azq
    PDB 2b0z-2boz
    PDB 2bpb-2ca3
    PDB 2ca4-2cz7
    PDB 2czs-2dyr
    PDB 2dys-2ewk
    PDB 2ewu-2fwl
    PDB 2fwt-2gl3
    PDB 2gln-2hhb
    PDB 2hhd-2ibn
    PDB 2ibz-2jb8
    PDB 2jbl-2mgh
    PDB 2mgi-2o01
    PDB 2o08-2ozy
    PDB 2p0b-2q0i
    PDB 2q0j-2r1h
    PDB 2r1k-2spm
    PDB 2spn-2vbd
    PDB 2vbp-2vzb
    PDB 2vzm-2wiv
    PDB 2wiy-2xj5
    PDB 2xj6-2ylj
    PDB 2yrs-2zon
    PDB 2zoo-3a17
    PDB 3a18-3aes
    PDB 3aet-3bnd
    PDB 3bne-3cir
    PDB 3ciu-3dax
    PDB 3dbg-3e1p
    PDB 3e1q-3eh4
    PDB 3eh5-3fll
    PDB 3fm1-3gas
    PDB 3gb4-3h57
    PDB 3h58-3hrw
    PDB 3hsn-3ir6
    PDB 3ir7-3k9y
    PDB 3k9z-3l4p
    PDB 3l61-3lxi
    PDB 3lyq-3mm8
    PDB 3mm9-3n62
    PDB 3n63-3nlo
    PDB 3nlp-3o0f
    PDB 3o0r-3p6o
    PDB 3p6p-3prq
    PDB 3prr-3sel
    PDB 3sik-3una
    PDB 3unc-4blc
    PDB 4cat-4erg
    PDB 4erm-4nse
    PDB 4pah-8cat
    PDB 8cpp-9nse

Permeability to Gases by Iron






Closely connected with the power to occlude gases is the property of transfusion, by virtue of which gases are able to pass through iron. In 1863 Cailletet showed that nascent hydrogen could pass through an iron vessel immersed in sulphuric acid at the ordinary temperature, and this has been confirmed by numerous later investigators.

This diffusion of nascent hydrogen is not inhibited even by a pressure of 14 atmospheres. Molecular hydrogen only passes through iron at a measurable velocity when the temperature is raised. Below 325° C. the velocity is inappreciable, at 350° C. it becomes perceptible, and at 850° C. the velocity is some forty times as great.

Iron is softened by prolonged exposure at 500° to 1000° C. to the transfusion of hydrogen, for the gas reduces and removes the small quantities of non-metallic impurities usually existing in the metal. Thus, for example, sulphur, phosphorus, and carbon are reduced and escape as volatile hydrides, the metal being purified to a corresponding extent.

The optimum temperature-range for this purpose lies between 950° and 1000° C., hydrogen containing small quantities of water vapour proving most efficient. The time of decarburisation is necessarily somewhat lengthy, and averages not less than some 4 or 5 days. The following results may be regarded as typical: -

Time of Decarburisation. Days.Carbon %Sulphur %
Before.After.Before.After.
40.0940.0760.0250.017
50.1820.0150.0300.017
40.3260.0270.0260.018
50.6830.0260.0160.006
51.050.0350.0110.003
121.670.2200.0420.008


No doubt if the decarburisation process were very greatly prolonged, the carbon and sulphur would be reduced to infinitesimal quantities. Analogous reactions take place between hydrogen and molten iron.


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