Effect of Magnetic Field on the Deposition of Transparent Diamond-Like Carbon ( DLC ) Films by RF-PCVD

In order to deposit transparent and hard DLC films, magnetic field was introduced to enhance the plasma density of radiofrequency plasma chemical vapor deposition (RF-PCVD). In this paper, the configuration and computation of external magnetic field B are introduced. The restriction effect of magnetic field B on the charged particles and the effect of magnetic field B on the primary parameters-nonindependent power Pf and self-bias Uz were also studied. The mechanism of how magnetic field B affects self-bias Uz was analyzed.     

High enhanced magnetization in carbon-doped Mn3Ga thin films

Carbon-doped Mn₃Ga thin films were grown on Si/SiO₂ substrates using rf magnetron sputtering technique. The tetragonal D0₂₂–type crystalline structure of ferrimagnetic Mn₃Ga is preserved on the Mn₃GaC_x films upon carbon concentrations up to x = 0.5, whereas higher concentrations lead to the formation of the antiperovskite Mn₃GaC phase. Geometry optimization calculations using the density functional theory were performed on a 2 × 2 × 2 Mn₃GaC_0.25 supercell with C in different positions in order to find that the most stable position for the C is interstitial octahedral site. Magnetic M(H) loops show that saturation magnetization M_s of Mn₃GaC_0.25 is enhanced to 200 kAm⁻¹ (from M_s = 90 kAm⁻¹ for undoped films). The increase of the C concentration leads to a reduction of the Curie temperature from 770 K to ∼420 K at the same time that the lattice cell suffers an expansion. The enhancement of M_s is explained in terms of a 90° ferromagnetic superexchange Mn-C-Mn interaction.     

Metallic interconnects for solid oxide fuel cell: A review on protective coating and deposition techniques

With the reduction of solid oxide fuel cells (SOFCs) operating temperature to the range of 600 °C–800 °C, metallic alloy with high oxidation resistance are used to replace traditional ceramic interconnects. Metallic interconnects is advantageous over ceramic interconnects; in terms of manufacturability, cost, mechanical strength, and electrical conductivity. To date, promising candidates for metallic interconnects are all Cr-containing alloys, which are susceptible to volatile Cr migration that causes cell degradation. As such, protective coatings have been developed to effectively inhibit Cr migration; as well as maintain excellent electrical conductivity and good oxidation resistance. This article reviews the progress and technical challenges in developing metallic interconnects; different types of protective coatings and deposition techniques for metallic interconnects for intermediate-temperature SOFC applications.     

Characterization of stainless steel parts by Laser Metal Deposition Shaping

Laser Metal Deposition Shaping (LMDS) is a new rapid manufacturing technology, which can build fully-dense metal components directly from the information transferred from a computer file by depositing metal powders layer by layer with neither mould nor tool. Typically, performed with stainless steel (SS) 316 powder, the orthogonal experiments combining with the ideal overlapping model were applied to ascertain the optimal processing parameters. Then the characteristics of microstructure, composition and phase of as-deposited cladding layers were analyzed through Scanning Electron Microscope (SEM) and X-ray diffraction (XRD), as well as relative model. Furthermore, the cooling rate and the solidification velocity during LMDS were evaluated based on empirical method. With the optimal parameters, some parts were fabricated without obvious defects, and then the mechanical properties of them were tested. Finally, the influencing regularities of critical parameters on microstructure and properties were concluded by comparison. The results prove that the microstructure of SS 316 deposits is composed of the slender dendrites growing epitaxially from the substrate, the mechanical properties are favorable and anisotropic, and the composition is uniform. Besides, the microstructure morphology and the mechanical properties are affected by the varied processing parameters at different degrees. Among them, the scanning speed shows the most remarkable effects on microstructure morphology, characteristic microscale, mechanical properties, as well as geometric shape of as-deposited parts.     

Review of suspension and solution precursor plasma sprayed thermal barrier coatings

As one of the promising methods that can be employed to fabricate high-performance thermal barrier coatings (TBCs), suspension plasma spraying (SPS) or solution precursor plasma spraying (SPPS) has received significant attention in academic research. Enhanced performances have been shown in the SPS-/SPPS-coatings due to their special microstructures, such as uniformly distributed micro-pores, vertical cracks or columnar structures. Since there are more complexities than conventional plasma spraying methods, many works have been devoted to study the mechanism and properties of SPS-/SPPS-coatings during the past decades. In this work, the latest development of SPS or SPPS is reviewed in order to discuss some key issues in terms of preparation of suspension or solution precursor, injection mode of liquid phase, interaction between liquid and plasma jet, microstructure of as-sprayed coatings and corresponding deposition mechanism. Meanwhile, the potential application of SPS or SPPS in some new-type TBCs is introduced at the end of this paper.     

Deposition of Nacystelyn from a Dry Powder Inhaler in Healthy Volunteers and Cystic Fibrosis Patients

The aim of this study was to compare, using gamma scintigraphy, the lung deposition of a novel mucoactive agent, Nacystelyn (NAL), administered as a dry powder inhaler (DPI) in six healthy volunteers, six adult patients with cystic fibrosis (CF), and six children and adolescents patients with CF. The correlation between in vitro and in vivo results was also tested. It was first demonstrated that the method of labeling of NAL with ^99mTc was reliable as tested by three in vitro methods (multistage liquid impinger, multistage cascade impactor, and 2-stage glass impinger). The deposition of unlabeled NAL, labeled NAL, and the radiolabel was similar in all stages of each device. Furthermore, the fine particle fraction (FPF) was the same on all apparatuses. The mean lung deposition obtained in volunteers was 27.5 ± 13.5%. The results are approximately three times higher than the results obtained previously in healthy volunteers with NAL metered-dose inhalers (MDIs). As expected, the lung deposition observed in patients with CF was lower, e.g., 23.5 ± 7.0% for adults and 16.5 ± 5.9% for children and adolescents. A significant correlation was found between lung deposition and both the patient weight (p < 0.02) and height (p < 0.04). Surprisingly, the peripheral:central (P:C) ratio was similar for the three populations, indicating that the presence of mucus in moderately ill patients with CF does not modify the lung distribution of NAL. The FPF measured in vitro was similar to that obtained in volunteers but higher than that found in both patient populations. The DPI formulation of NAL developed will probably improve patient compliance and comfort in future clinical trials and postmarketing use of the drug.     

Fabricating Ni–Mn–Ga microtubes by diffusion of Mn and Ga into Ni tubes

Tubes of the ferromagnetic shape-memory alloy Ni–Mn–Ga of composition near the Ni₂MnGa Heusler phase can be used, alone or combined in structures, in magnetic actuators or magnetic refrigerators. However, fabrication of Ni–Mn–Ga tubes with sub-millimeter diameter by classical cold or hot drawing methods is hampered by the brittleness of the alloy. Here, we demonstrate a new process, where Ni–Mn–Ga tubes are fabricated by interdiffusion of Mn and Ga into drawn, ductile Ni tubes with 500 and 760 μm inner and outer diameters. After interdiffusion and homogenization of Mn and Ga at 1000 °C for 24–36 h, Ni–Mn–Ga tubes with ∼300 and ∼900 μm inner and outer diameters were obtained with homogeneous radial composition distribution, independently of the diffusion sequences (i.e., Mn and Ga diffused sequentially or simultaneously). Longitudinal composition was uniform over lengths of ∼1 mm, but variable over longer length due to incomplete process control. For two of the three diffusion sequences, a sizeable (20–80 μm) region exhibiting Kirkendall pores formed at the outer surface of the tubes. Magnetization values as high as ∼60 emu/g were measured, which is comparable to the magnetization of the Ni₂MnGa Heusler phase. X-ray diffraction on the tube with the highest magnetization confirmed the room-temperature structure as cubic austenite.     

Comparative study of porous anodic alumina: effects of aluminium deposition methods

This article reports on the comparative study of the fabrication of porous anodic alumina films by anodisation of the aluminium films on glass substrates which were deposited by direct current sputtering and electron beam evaporation methods. The relationship between surface morphology of the deposited aluminum films and porous anodic alumina films was investigated. A more uniform and ordered porous anodic alumina was obtained by fabricating from electron beam evaporation deposited aluminium film with smaller and compact grains. Two-step anodisation was used to further improve the quality of porous anodic alumina compared to one-step anodisation. The optical transmittance spectra within wavelength of 370–800 nm were obtained and the optical properties were studied.     

Large sized cubic BN reinforced nanocomposite with improved abrasive wear resistance deposited by cold spray

In this work, large sized cubic BN (cBN) reinforced nanocomposites are prepared by cold spray deposition of blended powder mixtures of mechanically alloyed 40 vol.% cBN–NiCrAl nanocomposite particles and large sized cBN particles. Deposition behavior of the blended powders, microstructure and mechanical properties including hardness, fracture toughness and two-body dry abrasive wear behavior of the sprayed composites, are investigated. Results show that dense composites with large cBN particle content of 13–20 vol.%, depending on composition of the spray powders, can be obtained. Declining deposition efficiency is detected as increasing large cBN content due to the gradually enhanced sand blasting effect. Increasing content of large cBN in spray powder results in an increment in hardness and a decrement in fracture toughness. Abrasive wear resistance of the 40 vol.% cBN–NiCrAl nanocomposite is doubled by incorporating 20 vol.% of the large cBN particles. Worn surface morphology observation indicates that the improvement is due to the shielding effect of the large protruding cBN particles against SiC abrasive. Material removal mechanism of the sprayed composites during abrasive wear test is also studied.