Doctoral Dissertations

Chang Don Kim

Abstract

"The lattice constants of zone-refined iron filings and iron whiskers are 2.86623 and 2.86626 Å at 25°C respectively. Their thermal expansion coefficients are both the same, 12.1 x 10⁻⁶ /°C at temperatures 10 - 65°C.

The influence of hydrogen on the lattice constant of iron was investigated and it was found that hydrogen has no effect (within the limits of errors) on the lattice constant of iron at room temperature regardless of the charging methods. However, at elevated temperatures hydrogen expands the iron lattice due to increased solubility of the gas. The lattice constant of iron in vacuum and in a hydrogen atmosphere was determined at elevated temperatures and found to follow the empirical equations: in vacuum, a= 2.86522 + 4.28 x 10⁻⁵t and in hydrogen (under conditions of the experiments), a = 2.86554 + 2.45565 x 10⁻⁵t + 6.78828 X 10⁻⁸t² - 7.16922 x 10⁻¹¹ x t³ + 2.08773 x 10⁻¹⁴t⁴, where a is the lattice constant of alpha iron at temperatures between room and 910°C. The lattice constant of gamma iron in the range 910 - 1130°C is the same in vacuum and in hydrogen (under the conditions of the experiments) and follows the equation, a= 3.5771 +7.75 -5 x 10⁻⁵t, where a is the lattice constant at t°C. The thermal expansion coefficients of iron in vacuum are found to stay at a nearly constant value of 14.8 x 10⁻⁶ /°C in the range 200 - 800°C. In a hydrogen atmosphere under the conditions of the experiments it is found to have a maximum (17.3 x 10⁻⁶ /°C) at about 450°C. The effect of hydrogen on the lattice constant of iron at elevated temperatures is discussed.

The influence of hydrogen on the density and electrical resistivity of pure iron was investigated and it was found that hydrogen has an effect neither on the density of pure iron nor on its electrical resistivity between 100 and 600°C.

The density of zone-refined iron was determined to be 7.8745 ± 0.0002 g/cm³ at 25°C and the actual number of atoms per unit cell was calculated to be very close to the ideal number of two. Hence, the structure of zone-refined iron is sound or perfect.

The corrosion pattern of zone-refined iron in some acids (concentrated hydrochloric acid, 2 N sulfuric acid, 1.5 N nitric acid, 25 percent aqueous solution of aqua regia, and concentrated hydrofluoric acid) was studied and the following facts were found: (1) during corrosion of zone-refined iron, three main corrosion patterns develop on the surface and (2) all patterns consist of parallel steps and facets which are arranged in certain crystallographic orientations, and (3) the surface of these steps is mainly close to the planes (110) and (122), (112) and (123).

An anodic dissolution study of zone-refined iron in hydrochloric and sulfuric acids showed no measurable amount of anodic disintegration."--Abstract, pages ii-iv.

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Metallurgical Engineering

Publisher

University of Missouri at Rolla

Publication Date

1966

Pagination

xiii, 169 pages

Note about bibliography

Includes bibliographical references (pages 160-167).

Rights

© 1966 Chang Don Kim, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Corrosion and anti-corrosives -- Research
Expansion (Heat) -- Measurement
Crystal lattices

Thesis Number

T 1865

Print OCLC #

5973353

Electronic OCLC #

903904218

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