Developing GLAD Parameters to Control the Deposition of Nanostructured Thin Film

In this paper, we describe the device developed to control the deposition parameters to manage the glancing angle deposition (GLAD) process of metal-oxide thin films for gas-sensing applications. The GLAD technique is based on a set of parameters such as the tilt, rotation, and substrate temperature. All parameters are crucial to control the deposition of nanostructured thin films. Therefore, the developed GLAD controller enables the control of all parameters by the scientist during the deposition. Additionally, commercially available vacuum components were used, including a three-axis manipulator. High-precision readings were tested, where the relative errors calculated using the parameters provided by the manufacturer were 1.5% and 1.9% for left and right directions, respectively. However, thanks to the formula developed by our team, the values were decreased to 0.8% and 0.69%, respectively.

Ion energy-induced nanoclustering structure in a-C:H film for achieving robust superlubricity in vacuum

Hydrogenated amorphous carbon (a-C:H) films are capable of providing excellent superlubricating properties, which have great potential serving as self-lubricating protective layer for mechanical systems in extreme working conditions. However, it is still a huge challenge to develop a-C:H films capable of achieving robust superlubricity state in vacuum. The main obstacle derives from the lack of knowledge on the influencing mechanism of deposition parameters on the films bonding structure and its relation to their self-lubrication performance. Aiming at finding the optimized deposition energy and revealing its influencing mechanism on superlubricity, a series of highly-hydrogenated a-C:H films were synthesized with appropriate ion energy, and systematic tribological experiments and structural characterization were conducted. The results highlight the pivotal role of ion energy on film composition, nanoclustering structure, and bonding state, which determine mechanical properties of highly-hydrogenated a-C:H films and surface passivation ability and hence their superlubricity performance in vacuum. The optimized superlubricity performance with the lowest friction coefficient of 0.006 coupled with the lowest wear rate emerges when the carbon ion energy is just beyond the penetration threshold of subplantation. The combined growth process of surface chemisorption and subsurface implantation is the key for a-C:H films to acquire stiff nanoclustering network and high volume of hydrogen incorporation, which enables a robust near-frictionless sliding surface. These findings can provide a guidance towards a more effective manipulation of self-lubricating a-C:H films for space application.

Corrosion resistance evaluation of carbon and vanadium-based sputtered coatings on steel substrates

Steels are in constant contact with fluids that could generate corrosion regardless the application in which this steel is located. AISI-SAE 1045 like steels is widely used in different applications in engineering, even several of these parts made of this steel suffers wear processes. The synergy between corrosion and wear phenomena exacerbates the detriment of some physical properties of the material conducing it to a failure. A potential alternative to avoid this issue is to coat the material surface with an anticorrosive material, and among different techniques to produce coatings, physical vapor deposition ones are environmentally friendly, secure and with excellent properties on the final product. We report the production of coatings based on vanadium and carbon on AISI-SAE 1045 steels substrates varying some of the deposition parameters in a sputtering coatings machine. A 23-factorial design of experiments was done with power applied to the vanadium target, power applied to the carbon target and temperature as active factors with two levels each one. A relevant effect of the power applied to V target and temperature on the anticorrosive properties of the coatings was found, thus increasing these factors levels always gives higher surface roughness and higher corrosion rates, this result together provides an important insight into the values that must be considered to achieve good anticorrosive properties on the material. Overall, these results indicate that with low V target power and room temperature, and high C target power the lowest corrosion rates and roughness of the group are achieved, both results agree.

Bead Geometry Prediction in Laser-Wire Additive Manufacturing Process Using Machine Learning: Case of Study

In Laser Wire Additive Manufacturing (LWAM), the final geometry is produced using the layer-by-layer deposition (beads principle). To achieve good geometrical accuracy in the final product, proper implementation of the bead geometry is essential. For this reason, the paper focuses on this process and proposes a layer geometry (width and height) prediction model to improve deposition accuracy. More specifically, a machine learning regression algorithm is applied on several experimental data to predict the bead geometry across layers. Furthermore, a neural network-based approach was used to study the influence of different deposition parameters, namely laser power, wire-feed rate and travel speed on bead geometry. To validate the effectiveness of the proposed approach, a test split validation strategy was applied to train and validate the machine learning models. The results show a particular evolutionary trend and confirm that the process parameters have a direct influence on the bead geometry, and so, too, on the final part. Several deposition parameters have been found to obtain an accurate prediction model with low errors and good layer deposition. Finally, this study indicates that the machine learning approach can efficiently be used to predict the bead geometry and could help later in designing a proper controller in the LWAM process.

Characterizing the stress and electrical properties of superconducting molybdenum films

In the process of minimizing stress in sputtered Molybdenum (Mo) films for fabricating transition-edge sensor (TES) devices, we have investigated correlations between the stress and film deposition parameters. At a fixed sputtering power, the tensile stress of our film samples decreases toward both low and high ends of Ar pressure, suggestive of two physical mechanisms at work: an “atomic peening” effect at low Ar pressure and the development of voids at high Ar pressure. We have also carried out correlative studies of the stress and electrical properties (including superconducting critical temperature and residual resistivity) of the film samples, and found that the results are complex. We have made extensive comparisons with the published results, and attempted to explain the discrepancies in terms of film deposition techniques, sample preparation and treatment, and dynamical ranges of measurements. It is fairly clear that the microscopic properties, including porosity and disorder, of Mo films may have significant impact on the correlations.

The Effect of Working Gases Mixing Ratios on the Synthesis and Characteristics of TiO2/SiO2 Nanocomposite via Closed-Field unbalanced DC Magnetron Co-Sputtering Technique

The objective of this research is to study the influence of deposition parameters such as gases mixing ratio O2/Ar on the structural and optical properties of the TiO2/SiO2 nanocomposite films synthesized using closed field unbalanced dc magnetron co-sputtering technique. The nanocomposite thin films were characterized using x-ray diffraction (XRD) to determine the phase structure, and Fourier transform infrared (FTIR) spectroscopy to investigate Si-O-Si, Ti-O and Si–O–Ti. functional groups. The UV-VIS. absorption spectra of the synthesized films reveal that the indirect energy band gap was found to be 2.75 eV. The mixing ratio of Oxygen and Argon (O2/Ar) gases has a pronounced controlling effect on the structural and optical properties of such nanocomposite.

Recent Studies on the Fabrication of Multilayer Films by Magnetron Sputtering and Their Irradiation Behaviors

Multilayer films with high-density layer interfaces have been studied widely because of the unique mechanical and functional properties. Magnetron sputtering is widely chosen to fabricate multilayer films because of the convenience in controlling the microstructure. Essentially, the properties of multilayer films are decided by the microstructure, which could be adjusted by manipulating the deposition parameters, such as deposition temperature, rate, bias, and target–substrate distance, during the sputter process. In this review, the influences of the deposition parameters on the microstructure evolution of the multilayer films have been summarized. Additionally, the impacts of individual layer thickness on the microstructure evolution as well as the irradiation behavior of various multilayer films have been discussed.