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.

Thermal Insulation Properties of Hollow Y2O3:Eu Spheres Laminated with Er2O3

Currently, hollow sphere insulating materials are of importance for applications such as energy storage and savings and cryogenic engineering. The structures are formed by single hollow spheres, which can be joined, for example, by sintering. In this study, a 15 wt% Er-EDTA complex aqueous solution in which hollow Y2O3 spheres were mixed was used as the deposition body, and pencil spraying and sintering (PSS) was used to synthesize an Er2O3 hollow Y2O3 sphere composite film on a polished Si substrate. The structure of the composite film was successfully controlled by adjusting the 15 wt% Er-EDTA solution/hollow Y2O3 sphere mass ratio and the jet-to-substrate distance in the PSS process. In addition, the thermal insulation capability of the films was evaluated by the thermal steady-state method. The results show that the Er2O3/hollow Y2O3:Eu sphere composite films have a higher thermal insulation capability at a jet-to-substrate distance of 150 mm and a mass ratio (g) of 3.5:1. For the composite films with thicknesses of 38–92 µm, cross-sectional hollow ratio of 0.8–8.7% and void ratio of 6.3–13.1%, the temperature drop due to the porous (including hollow spheres and voids) structure films at 440°C is ΔTf =47°C. This is mainly associated with the film having more complicated microstructures. Therefore, the Er2O3/Y2O3:Eu composite film has good thermal insulation performance, and a simple preparation method for many kinds of hollow sphere films with complex structures and high porosities by using complex solutions with different compositions is provided.

Microstructure and Thermodynamic Analysis of Graphene-Reinforced Coating Surface

The microstructure of coatings with different graphene content and the hardness of cladding layer under different distance between coil and samples were investigated. The results showed that with the increase of graphene, the mean particle size of the powder did not get significantly coarser. The defects and oxides were appeared in the cladding layer and graphene diffused into the substrate. Distance between induction coil and sample has great impact on the hardness of coating, the higher hardness was measured in the distance between 6-8cm. The thermodynamic analysis of coating nucleation was carried out.

Influence of Various Target to Substrate Distances on the Structural and Optical Properties of Sputtered Gd-Doped ZnO Thin Films

The effect of various target to substrate distance on the physical properties of sputtered Gd-doped ZnO thin films were investigated. The thin films with three distances between a target to substrate ranged from 12.0, 13.5 and 15.0 cm were deposited by a dual-target sputtering method. All the thin film properties were characterized using x-ray diffraction, atomic force microscope, energy dispersive x-ray analysis and ultra-violet visible spectrophotometer. The sharp and intense peak of (002) was observed for a sample with the target to substrate distance of 13.5 cm which indicated good crystallinity as compared to other samples. Gd incorporations of 3 at% in ZnO films were further confirmed via the energy dispersive x-ray analysis. AFM images revealed that the surface topology Gd-doped ZnO thin film have a smooth and uniform surface. The transmittance was above 90 % and slightly decrease with the increase of target to substrate distance. The bandgap value was static at 3.14 eV for all the 12.0, 13.5 and 15.0 cm of various target to substrate distances.

Microstructure, Mechanical Properties and Tribological Behavior of Magnetron-Sputtered MoS2 Solid Lubricant Coatings Deposited under Industrial Conditions

Depositing MoS2 coatings for industrial applications involves rotating the samples during the PVD magnetron sputtering process. Here, we show that a 3-fold substrate rotation, along a large target–substrate distance given by the deposition unit, introduces porosity inside the coatings. The mechanical properties and wear behavior strongly correlate with the degree of porosity, which, in turn, depends on the temperature and the rotational speed of the substrate. Ball-on-disk tests and nanoindentation wear experiments show a consistent change in tribological behavior; first, a compaction of the porous structure dominates, followed by wear of the compacted material. Compaction was the main contributor to the volume loss during the running-in process. Compared to a dense coating produced without substrate rotation, the initially porous coatings showed lower hardness and a distinct running-in behavior. Tribological lifetime experiments showed good lubrication performance after compaction.

Effect of target-substrate distance on thickness and hardness of carbon thin films on SKD11 steel using target material from battery carbon rods

Carbon thin films on SKD11 steel were deposited by 40 kHz frequency plasma sputtering technique using a waste of battery carbon rods in argon plasma, and their mechanical properties were investigated by various target-substrate distances (1 cm, 1.7 cm, 2 cm, and 2.4 cm). The power used is 340 watts, the vacuum time is 90 minutes, and the gas flow rate is 80 ml/minute. The deposition time of carbon in plasma sputtering is 120 minutes with the initial temperature (temperature during vacuum) of 28 oC and the final temperature (the temperature after plasma sputtering) is 300 oC. The hardness value of SKD11 steel deposited with carbon thin films on SKD11 with target-substrate distance was tested using the Vickers microhardness test. Testing the thickness of the carbon thin films on the SKD11 steel substrate was carried out using a Nikon type 59520 optical microscope. Qualitative analysis of the thickness of the carbon thin films on the SKD11 steel substrate at a scale of 20 μm is shown by an optical microscope. Qualitatively, the thin film at a distance of 1.7 cm looks the brightest and thickest than other distance variations. Based on the Vickers microhardness test and Nikon type 59520 optical microscope, at the distance of 1 cm to 1.7 cm, the average thickness and hardness increased from 10,724 μm (286.6 HV) to 13,332 μm (335.9 HV). Furthermore, at the variation of the distance from 1.7 cm to 2.4 cm, the average thickness and hardness continued to decrease from 13.332 μm (335.9 HV) to 7.257 μm (257.3 HV). The possibility of interrupting atoms colliding with argon atoms in inert conditions increases at a long distance, thus causing the deposition flux on the SKD11 steel substrate to decrease