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Graphical abstract Highlights • Both (1 × 2) and (2 × 1) reconstructed Si(1 0 0):As surfaces can be prepared by MOCVD. • In situ RAS enables detailed process control even at elevated temperatures. • Si:As surface reactions strongly depend on the Si(1 0 0) substrate misorientation. • Atomically flat low-offcut Si(1 0 0):As-(1 × 2) surfaces with regular double-layer steps. • Arsenic atoms are considered to replace Si atoms during the adsorption process. Abstract Low-defect III-V integration on Si(1 0 0) requires atomically well-ordered heterointerfaces. To this end, we study the interaction of As with Si(1 0 0) surfaces and the formation of dimerized Si(1 0 0):As surfaces in situ with reflection anisotropy spectroscopy during metalorganic chemical vapor deposition (MOCVD). Control of surface processes allows us to intentionally 'rotate' the dimer orientation and choose between predominantly (1 × 2) and (2 × 1) reconstructed Si(1 0 0):As surfaces both for low and higher surface misorientation. We also verify that the (2 × 1) surface reconstruction becomes energetically more favorable for vicinal Si(1 0 0):As surfaces. We explain the preparation of Si(1 0 0):As surfaces displaying an almost single-domain, (1 × 2) reconstructed surface with an RMS roughness ≤1 Å and exhibiting broad, atomically flat terraces as well as regular double-layer steps. This surface is highly suitable for subsequent low-defect III-V integration. [ABSTRACT FROM AUTHOR]

We report on a convenient CVD fabrication of the uniform, compact and reproducible g-C 3 N 4 solid films on indium-tin oxide substrates. It is found that mixing quantitative thiourea into melamine as co-precursor prompts the deposition of greenish-yellow, transparent and smooth g-C 3 N 4 thin films. The thiourea apparently affects the crystalline, the surface morphologies and the energy band structures of g-C 3 N 4 films by modulating the polymerization process of the precursors, and simultaneously introduces S dopants into the g-C 3 N 4 films. Due to these roles of thiourea, the obtained S-doped g-C 3 N 4 films as a photoelectrode show a high and stable visible-light-driven photocurrent response. To further improve the photocurrent, the construction of three heterojunction structure types based on g-C 3 N 4 films is proposed and the corresponding charge transfer mechanisms are well discussed. The successful fabrication of high quality g-C 3 N 4 films in this work provides a footstone to construct the heterojunction film structures based on the carbon nitrides for the photoelectrochemical overall water splitting. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present the results of the prediction of the properties of PVD/CVD coatings with the use of finite element method (FEM) analysis. The possibility of employing the FEM in the evaluation of stress distribution in multilayer Ti/Ti(C,N)/CrN, Ti/Ti(C,N)/(Ti,Al)N, Ti/(Ti,Si)N/(Ti,Si)N, and Ti/DLC/DLC coatings by taking into account their deposition conditions on magnesium alloys has been discussed in the paper. The difference in internal stresses in the zone between the coating and the substrate is caused by, first of all, the difference between the mechanical and thermal properties of the substrate and the coating, and also by the structural changes that occur in these materials during the fabrication process, especially during the cooling process following PVD and CVD treatment. The experimental values of stresses were determined based on X-ray diffraction patterns that correspond to the modelled values, which in turn can be used to confirm the correctness of the accepted mathematical model for testing the problem. An FEM model was established for the purpose of building a computer simulation of the internal stresses in the coatings. The accuracy of the FEM model was verified by comparing the results of the computer simulation of the stresses with experimental results. A computer simulation of the stresses was carried out in the ANSYS environment using the FEM method. Structure observations, chemical composition measurements, and mechanical property characterisations of the investigated materials has been carried out to give a background for the discussion of the results that were recorded during the modelling process. [ABSTRACT FROM AUTHOR]

One of the major concerns related to machining of Ni-based super alloy is surface integrity since it directly affects the performance of the machined component during its intended application. In the current study, the influence of cutting speed (51, 84 and 124 m/min) and CVD multilayer tool coating (TiN/TiCN/Al 2 O 3 /ZrCN) on various aspects of surface integrity such as surface roughness, crystal structure and microstructure of the surface and sub-surface region, thickness of white layer and work hardening tendency have been investigated during dry turning of Incoloy 825. Particular emphasis has been given to understand the mechanism of formation of modified surface layer and the associated process of dynamic recrystallization. The study indicated coated tool resulted in better surface finish compared to that obtained with uncoated tool only at high cutting speed. Various macro features of machined surface included feed mark, material smearing, surface ploughing, re-deposited materials and chip debris. Transformation of crystallographic phase of the machined surface could not be detected compared to that of bulk material. Increase in cutting speed caused gradual refinement of grains, and increased white layer thickness. Coated tool, on the other hand, resulted in the generation of large number of nucleation sites and consequently finer grains at high cutting speed, whereas the uncoated tool promoted growth of sharply defined recrystallized grains. The coated tool prevented the formation of white layer at low and medium cutting speed and also decreased work hardening tendency of Incoloy 825 when compared with that of uncoated tool. [ABSTRACT FROM AUTHOR]

Polyether ether ketone (PEEK) has a similar elastic modulus to bone and can be a suitable alternative to metallic implants. However, PEEK is bioinert and does not integrate well with the surrounding tissues. The current commercial method for solving this problem is by coating PEEK substrates with calcium phosphates via plasma spraying. However, this method produces a low bonding strength between the substrate and the coating layer, as well as non-uniform density of the coating. In this study, chemical deposition was used to deposit HA crystalline particles on PEEK substrate without any subsequent crystallisation process therefore producing crystalline treated layer. EDX results confirmed the deposition of HA, and the XRD results confirmed that the treated layer was crystalline HA. FT-IR analysis confirmed the chemical bonding between HA and the substrate. Surface roughness increased from 24.27 nm to 34.08 nm for 3 min immersion time. The water contact angle showed an increase in wettability of the treated sample from 71.6 to 36.4 degrees, which in turn increased its bioactivity. The proposed method is a suitable alternative to other conventional methods as high temperature was not involved in the process which could damage the surface of the substrate. [ABSTRACT FROM AUTHOR]

Highlights: [•] Superhydrophobicity occurred with PTFE-AC-coated Al after intensified anodisation. [•] This coating exhibited own roughness features in the sub-/ low-micrometre ranges. [•] Polysiloxane coatings afforded smooth surfaces with incomplete water-repellence. [•] Artificial weathering resulted in a general worsening of the wetting behaviour. [•] Both coating types displayed strong differences in their sensitivity towards wear. [•] Cross-linkages between polymer chains are prerequisite for mechanically stable SH. [Copyright &y& Elsevier]

Highlights: [•] TiC/Ti(CN)/TiN multilayer coatings were grown on three high-strength steels using chemical vapor deposition (CVD). [•] The microstructure and hydrogen sulfide corrosion cracking behaviors were examined. [•] The coated sample show superior resistance to hydrogen sulfide stress corrosion cracking. [•] The coatings still maintain high hardness after corrosion test. [ABSTRACT FROM AUTHOR]

Highlights: [•] Single 5ns laser shots ablate CVD graphene with threshold fluence ~200mJ/cm2. [•] Damage threshold for UV irradiation depends strongly on sample. [•] Raman spectra indicate formation of oxidized graphene in ablated areas. [•] Oxidized graphene residues in ablated areas produce strong fluorescence. [ABSTRACT FROM AUTHOR]

Abstract: Titanium based alloys are used extensively for improving wear properties of different parts due to their high hardness contents. Titanium nitride (TiN) is among these coatings which can be deposited on surface using various techniques such as CVD, PVD and PACVD. Their weak interface with substrate is one major drawback which can increase the total wear in spite of favorite wear behavior of TiN. Disc shaped samples from AISI H13 (DIN 1.2344) steel were prepared in this study. Single TiN coating was deposited on some of them while others have experienced a TiN deposition by active screen plasma nitriding (ASPN). Hardness at the surface and depth of samples was measured through Vickers micro hardness test which revealed 1810Hv hardness as the maximum values for a dual-layered ASPN–TiN. Pin-on-disc wear test was done in order to study the wear mechanism. In this regard, the wear behavior of samples was investigated against pins from 100Cr6 (Din 1.3505) bearing steel and tungsten carbide–cobalt (WC–Co) steel. It was evidenced that the dual-layer ASPN–TiN coating has shown the least weight loss with the best wearing behavior because of its high hardness values, stable interface and acceptable resistance against peeling during wearing period. [Copyright &y& Elsevier]