Growth Of Sulfide Films Research Articles

The effects of chloride and sulphate on the growth of sulphide films on copper in anoxic sulphide solutions

AbstractThe corrosion of copper in chloride‐ and sulphate‐containing solutions containing sulphide (ranging from 5 × 10−5 M to 10−3 M) was studied by electrochemical impedance spectroscopy and the structure and physical properties of the copper sulphide deposits (Cu2S) were analysed by scanning electron microscopy. At low [SH−], a porous and non‐protective deposit was formed, and the low corrosion rates were limited by sulphide transport, partially within the deposit and partially in the bulk of the solution. At higher [SH−], the corrosion rates were much higher and initially more rapid in chloride‐containing than in sulphate‐containing solutions, suggesting a direct role for chloride in the interfacial corrosion process. When the copper sulphide deposit thickened, the rate became limited by CuI transport within the more compact and more crystalline deposit formed. Changes in the morphology of the deposit suggest that chloride adsorption on the surfaces of the deposit inhibited the incorporation of Cu3S3 clusters, transported from the corroding copper surface, into the growing crystals.

The nature of the copper sulfide film grown on copper in aqueous sulfide and chloride solutions

AbstractIn this paper, the properties of copper sulfide films formed both anodically and naturally in deaerated/anoxic aqueous sulfide and chloride solutions were investigated using a series of electrochemical and surface analytical techniques. A combination of cyclic voltammetric, corrosion potential (Ecorr), and cathodic stripping voltammetric experiments showed that the sulfide film growth kinetics and film morphologies were controlled by the supply of SH− from the bulk solution to the copper surface. There was no passive barrier layer observed on the copper surface under either electrochemical or corrosion conditions. The film morphology was dependent on the type and concentration of anions (SH−, Cl−) present in the solution. Scanning electron microscopy on both surfaces and focused ion beam‐cut cross‐sections showed the growth of a thin, but porous, base layer of chalcocite (Cu2S) after short immersion periods (up to 2 hr) and the continuous growth of a much thicker crystalline outer deposit over longer immersion periods (≥36 hr), suggesting a solution species transport‐based film formation process and the formation of an ineffective thin “barrier‐type” layer on copper.

The Susceptibility of Copper to Pitting Corrosion in Borate-Buffered Aqueous Solutions Containing Chloride and Sulfide

The formation of sulfide and oxide films on copper (Cu) was studied in chloride solutions with and without added borate and sulfide. Electrochemical experiments demonstrated that Cu sulfide (Cu2S) films formed at considerably lower potentials than oxides (Cu2O/CuO) films. The growth of Cu2S was controlled by a combination of sulfide transport to the reacting Cu surface and the competition between SH− and Cl− ions for adsorption sites on the Cu surface. Scanning electron microscopy on focused ion-beam cut cross sections demonstrated that the films were porous and not passive. At more positive potentials, Raman spectroscopy and X-ray photoelectron spectroscopy demonstrated that the formation of oxide films, likely with the formation of a passive oxide film, dominated over anodic dissolution of Cu as CuI chloride complexes when the borate to chloride concentration ratio was sufficiently high. If pitting is to occur on Cu, it will require oxide not sulfide film growth.

Modification of the properties of tin sulfide films grown by spray pyrolysis

n-Type SnS and SnS2 sulfide films up to 0.6 μm in thickness, with resistivity in the range 2 ≤ ρ ≤ 17 kΩ cm have been grown by spray pyrolysis of aqueous solutions of the SnCl2 ∙ 2H2O, SnCl4 ∙ 5H2O, and (NH2)2CS salts at substrate temperatures in the range 523 ≤ Ts ≤ 623 K. At constant thermal conditions of sulfide film growth, varying the chemical composition of the solutions for spray pyrolysis makes it possible to obtain films with substantially different optical properties. Undoped SnS and SnS2 have high transmittance, T ≈ 40–70%, and a sharp intrinsic absorption edge. The optical band gap of the SnS and SnS2 sulfide films has been shown to depend on film growth conditions.

Nucleation and mechanism of metal sulfide film growth using deposition by thiocarbamide

The mechanism of hydrolytic decomposition of thiocarbamide upon the interaction with metal salts with deposition of thin films of sulfide was proposed. The kinetic studies of the transformation of metal salt into sulfide and IR spectroscopy confirmed that one of the hydrolysis products of thiocarbamide was cyanamide. The concept about the activation of thiocarbamide decomposition was extended due to the nucleophilic addition of anions to form an intermediate reaction complex thiocarbamide—metal ion—nucleophile. The activation weakens in the order OH− > CH3COO− > Cl− > Br− > I−. The presence and active role of colloidal components of reaction mixtures in the nucleation and formation of films of metal sulfides by chemical bath synthesis were established by spectrophotometric and kinetic measurements. It was concluded that from the viewpoint of fractal formalism metal sulfide films are formed in chemical bath deposition via the mechanism of cluster—cluster aggregation in the form of consecutive evolution of structural levels. A complex scheme of the mechanism of chemical bath deposition of metal sulfides by thiocarbamide was proposed. The results of studies of their phase composition, microstructure, and properties are presented.

Investigation of metal sulfide optical thin film growth in low-loss IR hollow glass waveguides

In this study, the film growth kinetics for near and mid-IR reflection enhancing CdS and PbS dielectric thin films in HGWs is experimentally established. Crucial fabrication parameters including solution concentrations, pH, and fluid velocity are optimized. The film thickness of these films in HGWs is studied as a function of deposition time and temperature. Through IR spectral response analysis, the dielectric thin film thicknesses were determined and found to have a strong linear time dependence. Accurate metal sulfide film growth models in HGWs were developed, allowing for direct determination of necessary deposition times to yield metal sulfide HGW thin film coatings having a desired response.

Investigation of AISI 1040 steel corrosion in H 2S solution containing chloride ions by digital image processing coupled with electrochemical techniques

This paper presents a study of AISI 1040 steel corrosion in aqueous electrolyte of acetic acid buffer containing 3.1 and 31 × 10 −3 mol dm −3 of Na 2S in both the presence and absence of 3.5 wt.% NaCl. This investigation of steel corrosion was carried out using potential polarization, and open-circuit and in situ optical microscopy. The morphological analysis and classification of types of surface corrosion damage by digital image processing reveals grain boundary corrosion and shows a non-uniform sulfide film growth, which occurs preferentially over pearlitic grains through successive formation and dissolution of the film.

Subnanometer-Thick PbS Film on Organic Substrate and Its Usage as Buffer for Homo- and Heteroepitaxial Overgrowth

We report on the fabrication of a subnanometer-thick epitaxial PbS film on polydiacetylene (PDA) substrate. The film is formed by cation-absorption in PbCl2 solution followed by sulfidation in mixed H2S/N2 gas, exhibiting a flat and smooth surface morphology. The strong adsorbate-surface interaction between the lead hydrolysis complexes and the carboxyl headgroups on the surface of PDA accounts for such a growth mode. We further demonstrate that such an ultrathin film can be used as a buffer layer for both homo- and heteroepitaxial growth of sulfide films. The X-ray and electron diffraction results reveal that the (001) planes of PbS are parallel to the surface of PDA and the (110) planes of PbS are parallel to the (110) planes of PDA.

Microstructural Studies of the Initial Stages of Copper Sulfide Film Growth: Influence of Humidity

Microstructural Studies of the Initial Stages of Copper Sulfide Film Growth: Influence of Humidity

Ellipsometrical study of indium sulfide film growth process on InP

The process of indium sulfide film growth on indium phosphide substrates in a quasi-closed volume is investigated by ellipsometric methods. An original ellipsometric technique is suggested for the investigation of optically inhomogeneous structures based on multiangle measurements of Ψ and Δ parameters with an independent determination of the complex reflection factor of the film. The kinetics of In2S3 film growth on InP is shown to be determined by a linear-parabolic law, and the optical inhomogeneity of the film thickness is considered to be associated with the non-uniform distribution of sulfur in the films. [Russian Text Ignored]

Mechanism and Theories of Rubber Adhesion to Steel Tire Cords—An Overview

Abstract An overview is given of the mechanism and theories of adhesion of brass-plated steel cords to rubber. The literature on this topic in the period 1979–1983 is reviewed. Although the actual type of bond between the interfacially formed copper sulfide film and the cured network still has not been identified conclusively, this aspect of rubber-brass adhesion is becoming rather irrelevant since the literature is unanimous that bond failure seldom occurs adhesively, i.e., between CuxS and rubber, but usually cohesively within the sulfide film or adhesively at the interface sulfide-substrate. A model is described in which most of the recent findings are incorporated. In this model, brass develops a high bond strength to NR as a result of the in situ growth of a thin (≤50 nm) copper sulfide film onto the brass during the early stages of the cure before crosslinking sets in. This sulfide film has good adhesive and cohesive properties but is, on the other hand, so porous that rubber molecules become entangled in this film (interlocking model). ZnS or FeS are considered nonbonding because they lack the microporosity required for interlocking. Synchronization of sulfide growth and rubber cure is not required. The major prerequisite is that sulfide film growth has been completed before cross-linking begins. Previous rubber oxidation theories and the effect of CuxS on crosslink density of rubber adjacent to the cord surface are also discarded for lack of experimental evidence. Ultimate bond strength and bond durability are determined by cord and by compound properties. Optimum cord parameters are predicted by the model as a thin brass coating with a high concentration of diffused iron, a low copper content (60–65%) and a thin but very homogeneous ZnO surface layer which is passivating and which contains copper atoms. Copper oxides are undesirable. The homogeneous ZnO film improves the cords' corrosion resistance, the included Cu atoms are required for rapid initial CuxS formation and prevention of non-bonding ZnS formation. The major compound parameter is the sulfur-to-accelerator ratio. There is evidence that brass is sulfidized by intermediates of the type R-S-Sy-NR where R is an accelerator fragment, rather than by free sulfur. The properties of the CuxS film, such as adhesion, cohesion and stability in corrosive environments depend on the type of CuxS formed. High values of y in the intermediate lead to good CuxS films, low values produce poor films, regardless of the quality of the cord.