Review of Thermal Spray Coating Applications in the Steel Industry: Part 1—Hardware in Steel Making to the Continuous Annealing Process

This two-part article series reviews the application of thermal spray coating technology in the production of steel and steel sheet products. Part 2 of this article series is dedicated to coating solutions in the continuous galvanizing line. The corrosion mechanisms of Fe- and Co-based bulk materials are briefly reviewed as a basis for the development of thermal spray coating solutions. WC-Co thermal spray coatings are commonly applied to low Al-content galvanizing hardware due to their superior corrosion resistance compared to Fe and Co alloys. The effect of phase degradation, carbon content, and WC grain size are discussed. At high Al concentrations, the properties of WC-Co coatings degrade significantly, leading to the application of oxide-based coatings and corrosion-resistant boride containing coatings. The latest results of testing are summarized, highlighting the critical coating parameters.     

Selection of a Relaxation Function to Describe the Dissipative α-Relaxation Process in Latex Polymers

Protection of Metals and Physical Chemistry of Surfaces - Discrete relaxation times D(τ) in latex polymers are calculated using the phenomenological model of a standard linear body and...     

Evolution of Microstructure and Mechanical Properties of Steel Under a Combined “Helical Rolling – Pressing” Process

Metal Science and Heat Treatment - The structure and mechanical properties of steel 45 are studied after “helical rolling – pressing” combined deformation. It is shown that the...     

Erratum to: “Synthesis of Aza-Pseudopeptides and the Evaluation of their Inhibiting Efficacy of Mild Steel Corrosion in 1.0 M HCl”

Protection of Metals and Physical Chemistry of Surfaces - The name of the second author should read A. M. Elhorri.     

The Process of “Made in China”in the Valve Manufacturing Industry

Valve industry,being the vital link in the manufacturing industry,plays a significant role in the development of national economy. Due to the gap between China and the advanced level internationally in valve manufacturing,many key valves with high parameters,high temperature and pressure rely on the imports. Tostrengthen the localization of valve manufacturing,and after implementing the document     

KCl-Induced Corrosion of a 304-type Austenitic Stainless Steel in O2 and in O2 + H2O Environment: The Influence of Temperature

The oxidation of the 304-type (Fe18Cr10Ni) austenitic stainless steel was investigated in the temperature range 400–600 °C in 5% O₂ and 5% O₂ + 40% H₂O. Exposure time was up to 1 week. Prior to exposure, the polished samples were coated with 0.1 mg/cm² KCl. Uncoated samples were also exposed and used as references. The oxidized samples were analyzed by gravimetry and by ESEM/EDX, XRD, IC and AES. The results show that KCl is strongly corrosive. Corrosion is initiated by the reaction of KCl with the chromia-containing oxide that normally forms a protective layer on the alloy. This reaction produces potassium chromate particles, leaving a chromium-depleted oxide on the alloy surface. At 500 and 600 °C this results in rapid oxidation, resulting in the formation of a thick scale consisting of a mixture of hematite, spinel oxide ((Fe,Cr,Ni)₃O₄) and K₂CrO₄. The thick scale is poorly protective and permeable to e.g. chloride ions. The KCl-induced corrosion of alloy 304L in dry O₂ and in an O₂ + H₂O mixture increases strongly with temperature in the range 400–600 °C. The strong temperature dependence is explained partly by the temperature dependence of the chromate-formation reaction and partly by the ability of the chromium-depleted oxide to protect the alloy at low temperature. At 400 °C, the oxide was still protective after 168 h.     

Development of methods of investigation of the interfacial layer in “iron-protective nanoscale polymer film” systems

The application of double-layer substrate from ⁵⁶Fe nonresonance isotope and ⁵⁷Fe ultrafine layer allows one to use Mössbauer spectroscopy to investigate the interfacial area in the “iron-nanoscale polymer film” system. The anodic dissolution of iron substrate is used to investigate the interfacial layer by X-ray photoelectron spectroscopy.     

The Role of Cu(I) in the Process of Forming Cu2–xS Coatings by a Chemical Route

The interaction of the Cu₂O adsorbed with Na₂S_n (n = 1–4), during formation of the Cu_2–xS coatings has been investigated by cyclic voltammetry.

The summarized reaction of this process has been shown to correspond to the equation:

Na₂S_n + Cu₂O_ad + H₂0 → Cu₂S_ad + (n–1)S^o + 2NaOH,

where S^o/Cu=(n–1)/2. Such a stoichiometry of reaction can be explained by the formation of an intermediate—the adsorbed polysulphide of Cu(I)—and by its subsequent decomposition into Cu₂S and S^o.

When a thicker coating is being formed, i.e., when the surface being coated is repeatedly immersed into an ammoniate solution of Cu(I) and S^o fully bounded:

S^o_ad + 2 Cu⁺ → CuS + Cu²⁺.

At the same time due to different solubility products (L=2.5·10^?48 and 6.3·10^?36 for Cu₂S and CuS respectively), an exchange

CuS_ad + 2(1–x)Cu⁺ → Cu_2–xS_ad+ (1–x)Cu²+ occurs.

After formation of Cu²⁺, parallel processes characteristic for the interaction of Cu(II) with Na₂S_n start to take place, during which S^o is also formed.     

Reply to “Comment on the role of intragranular dislocations in superplastic yttria-stabilized zirconia”

This paper replies to a comment by Balasubramanian and Langdon on our studies of yttria-stabilized zirconia. Their conclusion conflicting with experimental facts may arise from contradictions in their analysis. Microstructural aspects indicate that the deformation occurs through grain boundary sliding rather than interface-controlled Coble creep.     

IFHTSE Global 21: heat treatment and surface engineering in the first decades of the twenty-first century: Part 2 – Heat treatment in China: present and future

Abstract

The large state-owned enterprises in China have achieved great progress in heat treatment production technologies over the last 10 years. In addition, the number of smaller commercial heat treatment plants has increased rapidly to more than 3000. Heat treatment plant and equipment manufacturing flourishes. However, because China covers a vast territory with uneven regional development, and consequently little uniformity across the individual enterprises, there are still obvious gaps compared with the advanced level globally. Therefore the 11th Five-Year Plan for the heat treatment industry, formulated by the China Heat Treatment Association (CHTA) and the Chinese Heat Treatment Society (CHTS) prioritises equipment renovation as the way ahead for production technology innovation. Based on a nation-wide survey, the 11th Five-Year Plan described the current status, identified the shortcomings, formulated the guiding principles and directions for development, and put defined key R&D initiatives and other measures for achieving progress. A vision up to 2020 was set out.     

IFHTSE Global 21: heat treatment and surface engineering in the first decades of the twenty-first century: Part 1 – Introduction to ongoing IFHTSE activity

Abstract

Engineering systems and components are the result of a complex chain of actions, starting with a design to match the functional demands: materials science and technology are intimately involved; there are often multiple stages in the manufacturing process, as well as essential quality assurance methods for the component and system. Each step in the process has significance; optimum outcomes and cost effectiveness depend heavily on their being orchestrated and managed as an integrated sequence. Depending on the circumstances, the relative importance of each step may be viewed differently, but the heat treatment and surface engineering manufacturing processes are always likely to be critical. These processes themselves represent a complex balance of materials, technology, energy and environmental factors to achieve an optimum combination of functionality, industrial feasibility and economic and social viability.     

Investigation on the effectiveness of the repair method 8.3 “Corrosion protection by increasing the electrical resistivity” in chloride-containing concrete Part 2: Chloride redistribution in concrete after application of a system sealing surface protective coating

This DFG-funded research project aimed to gain a better understanding of the mechanisms of the W-Cl repair principle within the framework of fundamental investigations, to contribute to the creation of the necessary basis for a broader application of the repair principle in practice. The focus was on the development of a model to describe the chloride redistribution after the application of a system sealing surface protective coating. On the basis of Fick's second law of diffusion, a mathematical model with a self-contained analytical solution was developed, with the help of which the chloride redistribution after application of a system sealing surface protective coating can be calculated under the idealized assumption of complete water saturation of the concrete. Furthermore, the influence of the dehydration of the concrete, expected as a result of the application of the repair principle W-Cl, on the chloride redistribution was investigated. On the basis of laboratory tests and numerical simulations, material-specific reduction functions were developed to quantify the relationship between the chloride diffusion coefficient and the ambient humidity.