Uniform Coatings Research Articles

Effect of energy, temperature, and Cu-doped coatings on crystallinity of Hydroxyapatite thin films obtained by pulsed laser deposition

In this work, a pulsed laser deposition (PLD) technique with an Nd:YAG laser source was used to produce pure Hydroxyapatite (HA) and Cu-substituted HA (Cu-HA) coatings on stainless steel substrates in vacuum at room temperature. It is observed that the combined effects of percentages of Cu dopants and laser energy as well as annealing temperature significantly modify the crystallinity of the films. The morphology and structural properties of the deposited HA films were analyzed by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Raman spectroscopy. FESEM images displayed various shapes of nanoparticles with high-surface density throughout the area of the substrate and with typical sizes around 26–208 nm. XRD analysis confirmed that post-deposition annealing is essential to achieve the desired crystallinity and uniformity of coatings. The Raman spectrum of HA has peaks at 958.22, 437.48, and 587.05 cm[Formula: see text] attributed to the [Formula: see text] PO[Formula: see text], [Formula: see text] PO[Formula: see text], and [Formula: see text] PO[Formula: see text], respectively. The synthesized HA and Cu-HA crystalline films are nanostructures with dense and compact microstructures. Finally, irregular surface and crystalline structure of fabricated films lead to the extension of the surface and enhance the cell’s proliferation in medical uses and biomedical applications.

Back Cover: Nanoscale electrodeposition: Dimension control and 3D conformality (EXP2 3/2021)

Ho Won Jang and co-workers review the feasible dimensional/morphological control of electrodeposition and uniform coatings on complicated 3D nanostructures using diverse materials. With the significant advances in the nanoscale design of the materials through electrodeposition, their applicability toward various devices is introduced from the commercial point of view.

Non-stoichiometric gallium oxide with cubic structure directly integrated to C-Cut sapphire

We used oxygen-reactive electron beam evaporation and post-deposition thermal treatment to prepare thin films of gamma-phase gallium oxide (γ-Ga2O3) grown on c-cut sapphire substrates. Films were prepared at room temperature under different partial pressures of oxygen present (from 1.0 mPa to 8.0 mPa). After thermal treatments at 600.0 °C for 30 min, the films have different surface morphologies, which is evidences by atomic force microscopy. Scanning electron microscopy with energy dispersive spectroscopy analyses reveal the formation of non-stoichiometric Ga2O3 films, that uniform coat the substrates. X-ray diffraction analyses reveal the formation of γ-Ga2O3-x (0.4 < x < 0.6) with crystalline planes (001) preferably oriented parallel to the substrate surface but slightly tilted (less than ± 0.2°) in relation to the direction [001] of the c-cut sapphire substrates. Raman spectroscopy suggest that films despite structurally oriented present high degree of chemical disorder but with no evidence of other Ga2O3 polytypes formation. Such a simple route for the preparation of non-stoichiometric γ-Ga2O3 is promising for several catalytic applications and developments of light emitting devices.

Versatile Thiol- and Amino-Functionalized Silatranes for in-situ polymerization and Immobilization of Gold Nanoparticles

BackgroundOrganosilanes have been massively implemented as building blocks in the fields of sol–gel material synthesis, surface functionalization, and nanotechnology. However, organosilane has been humbled by limitations, such as poor reproducibility, fast hydrolysis and heterogeneous molecular orientation. An emerging silatrane is gaining tremendous interest due to the unique tricyclic caged structure and transannular N→Si dative bond to provide chemical stability in aqueous solution and controllable deposition on surfaces. MethodsAminopropyl silatrane (APS), Mercaptopropyl silatrane (MPS) and 3-Mercaptopropyl trimethoxysilane (MPTMS) were applied to modification of silicon oxide substrates to in-situ graft hydrophilic polymers and immobilize gold nanoparticles (AuNPs). Thin and uniform silatrane coatings have been proved by atomic force spectroscopy, ellipsometry and X-ray photoelectron spectroscopy. Significant FindingsAntifouling poly(ethylene glycol) methacrylate (PEGMA) was grafted separately on MPS and MPTMS via surface-initiated thiol-ene photopolymerization. We found that MPS-PEGMA films were 30% superior to MPTMS-PEGMA films in protein repellency. Moreover, APS and MPS were co-deposited to attract and conjugate gold nanoparticles. AuNPs cluster size on APS films was found to increase 3.43 times along with broader AuNPs absorbance peaks after acid treatment, whereas cluster size increased only 4% on mixed silatrane-modified films. These discoveries are pertinent to robust and versatile properties that silatrane offers.

Nanoscale electrodeposition: Dimension control and 3D conformality.

Electrodeposition with a long history has been considered one of the important synthesis techniques for applying various applications. It is a feasible route for fabricating nanostructures using diverse materials due to its simplicity, cost-effectiveness, flexibility, and ease of reaction control. Herein, we mainly focus on the nanoscale electrodeposition with respect to dimension control and three-dimensional (3D) conformality. The principles of electrodeposition, dimensional design of materials, and uniform coatings on various substrates are presented. We introduce that manipulating synthesis parameters such as precursors, applied current/voltage, and additives affect the synthesis reaction, resulting in not only dimensional control of materials from three-dimensional structures to zero-dimensional atomic-level but also conformal coatings on complicated substrates. Various cases regarding morphology control of metal (hydro)oxides, metals, and metal-organic frameworks according to electrodeposition conditions are summarized. Lastly, recent studies of applications such as batteries, photoelectrodes, and electrocatalysts using electrodeposited materials are summarized. This review represents significant advances in the nanoscale design of materials through methodological approaches, which are highly attractive from both academic and commercial aspects.

Microwave plasma oxidation of near-equiatomic NiTi alloy for obtaining low-Ni TiO2 coating

In this paper, microwave plasma oxidation (MPO) treatment was carried out on near-equiatomic NiTi alloy for the first time, in order to reduce Ni content and improve cytocompatibility on its surface. The specimens were oxidized at 600 °C for 10, 30, and 60 min, named MPO-1, MPO-2, and MPO-3, respectively. The differences in surface properties, corrosion resistance in DMEM, protein adsorption, and cytocompatibility between the MPO-treated specimens and original substrate were investigated. The results showed that uniform and dense rutile TiO2 coatings with nano-sized granular structures could be formed on the NiTi surface under all MPO time. The Ni/Ti ratio on the MPO-treated surfaces was reduced to ~0.04, close to zero. For MPO-1 and MPO-2, a Ni-rich layer with Ni content of ~70 at.% was formed underneath the outermost TiO2 layer, while an extra high Ni-rich layer with Ni content of ~90 at% was formed between them for MPO-3. Due to the dense TiO2 coating and suitable nanostructure on the surface structure, MPO-2 possessed better corrosion resistance in DMEM and biocompatibility than the original substrate, MPO-1, and MPO-3. Besides, the oxidation rate of MPO treatment is higher than that of other oxidation methods, such as thermal oxidation. That is, the proposed MPO treatment is an oxidation method with high efficiency and effectiveness.

Limitations of Ultrathin Al2O3 Coatings on LNMO Cathodes.

This study demonstrates the application of Al2O3 coatings for the high-voltage cathode material LiNi0.5–xMn1.5+xO4−δ (LNMO) by atomic layer deposition. The ultrathin and uniform coatings (0.6–1.7 nm) were deposited on LNMO particles and characterized by scanning transmission electron microscopy, inductively coupled plasma mass spectrometry, and X-ray photoelectron spectroscopy. Galvanostatic charge discharge cycling in half cells revealed, in contrast to many published studies, that even coatings of a thickness of 1 nm were detrimental to the cycling performance of LNMO. The complete coverage of the LNMO particles by the Al2O3 coating can form a Li-ion diffusion barrier, which leads to high overpotentials and reduced reversible capacity. Several reports on Al2O3-coated LNMO using alternative coating methods, which would lead to a less homogeneous coating, revealed the superior electrochemical properties of the Al2O3-coated LNMO, suggesting that complete coverage of the particles might in fact be a disadvantage. We show that transition metal ion dissolution during prolonged cycling at 50 °C is not hindered by the coating, resulting in Ni and Mn deposits on the Li counter electrode. The Al2O3-coated LNMO particles showed severe signs of pitting dissolution, which may be attributed to HF attack caused by side reactions between the electrolyte and the Al2O3 coating, which can lead to additional HF formation. The pitting dissolution was most severe for the thickest coating (1.7 nm). The uniform coating coverage may lead to non-uniform conduction paths for Li, where the active sites are more susceptible to HF attack. Few benefits of applications of very thin, uniform, and amorphous Al2O3 coatings could thus be verified, and the coating is not offering long-term protection from HF attack.

An efficient method for enhancing adhesion and uniformity of Al2O3 coatings on nickel micro-foam used in micropacked beds

• An efficient coating method to overcome the capillary force was proposed. • The pore size on substrate surface can be controlled by the pretreatment conditions. • Correlation was proposed with excellent practicality for predicting the pore size. • Squeezing of Al 2 O 3 particles in the pores can improve the adhesion of coatings. Methods of coating Al 2 O 3 on nickel micro-foam were compared and screened, aiming to overcome the capillary force and prepare the micro-foam monolithic catalyst coatings. The surface of micro-foam substrate was pretreated by a chemical etching method to improve the adhesion of the coatings on the substrate. The results showed that the slurry circulation at 162 ml·min −1 was evaluated as the optimal method. The pore size on the substrate surface can be controlled by changing the pretreatment conditions. An empirical correlation was also proposed, showing an excellent practicality for predicting the pore size. The adhesion of the coatings with substrate pretreatment was significantly better than that without substrate pretreatment. The minimum value of mass loss after ultrasonic vibration was 3.9%. This mainly attributes to the squeezing of Al 2 O 3 particles in the pores of substrate surface. The coatings on nickel micro-foam are hopefully used in micropacked beds for catalytic reactions.

Improved tribological properties, cyto-biocompatibility and anti-inflammatory ability of additive manufactured Ti-6Al-4V alloy through surface texturing and nitriding

Surface texture and nitride coating have been proved as effective ways to improve the tribological properties of biomedical titanium alloys. However, the influence of surface texture and nitride coating on cells behavior, especially on the polarization of macrophages, was rarely reported. In this work, Ti-6Al-4V parts with designed rhombus surface texture were successfully prepared by selective laser melting process. Followed by post heating treatment in N2, uniform and dense nitride coatings on the textured surfaces consisted of TiN, Ti2N, TiN0.9 and N-containing solid solution with a thickness of ~5 μm were generated. The combination of surface texture and nitride coating reduced the frictional coefficient from 0.343 to 0.166, and significantly improved the wear resistance of the substrate. The nitride coating promoted the adhesion and proliferation of MC3T3-E1 cells in the early stages (1 d and 3 d). Textured surfaces provided larger area for cells growth that encouraged the cell adhesion and early spread. The significant increasing of the expression of Arg-1 and the ratio of CD206 positive cells (M2 phenotype) comparing with the uncoated group indicated that the nitride coating promoted the macrophages (Raw264.7 cells) polarization into anti-inflammatory type after co-culturing for 24 h. Surface texture combined with nitride coating further increased the ratio of CD206 positive cells and also reduced the inflammatory factors releasing.

The effect of acetylene flow rate on the uniform deposition of thick DLC coatings on the inner surface of pipes with different draw ratios

Thick multilayered DLC coatings were deposited on the inner surface of pipes with different draw ratios by hollow cathode plasma immersion ion processing (PIIP). By tuning the acetylene (C2H2) flow rate, the change of plasma density caused by different draw ratios can be compensated to fulfill the uniform deposition of thick DLC coatings along the pipes. The influence of C2H2 flow rate on the mechanical and tribological properties of the DLC coatings were investigated. With the increase of draw ratio, the deposition temperature and gas pressure declined, and the plasma density became more asymmetrical in the axial direction. Increasing the flow rate can timely replenish the plasma inside the pipe and resolve the mass depletion problem, resulting in better thickness and structure uniformity of the DLC coatings. The greatest deposition rate of 28.6 μm/h was obtained at the 250 sccm C2H2 flow with a draw ratio of 5:1. The results of Raman spectrum and XPS indicated that the content of sp2-carbon bonds decreased with the increasing draw ratio for lower impact energies of ions. The higher sp3 carbon bonds content contributed to the formation of carbonaceous transfer layers, which resulted in the lower friction coefficient and wear rate.

A Uniform and Robust Bioinspired Zwitterion Coating for Use in Blood-Contacting Catheters with Improved Anti-Inflammatory and Antithrombotic Properties.

Inflammation and thrombosis are two major complications of blood-contacting catheters that are used as extracorporeal circuits for hemodialysis and life-support systems. In clinical applications, complications can lead to increased mortality and morbidity rates. In this work, a biomimetic erythrocyte membrane zwitterion coating based on poly(2-methacryloyloxyethyl phosphorylcholine-co-dopamine methacrylate) (pMPCDA) copolymers is uniformly and robustly modified onto a polyvinyl chloride (PVC) catheter via mussel-inspired surface chemistry. The zwitterionic pMPCDA coating exhibits excellent antifouling activity and resists bacterial adhesion, fibrinogen adsorption, and platelet adhesion/activation. The material also demonstrates great hemocompatibility, cytocompatibility, and anticoagulation properties in vitro. Additionally, this biocompatible pMPCDA coating reduces in vivo foreign-body reactions by mitigating inflammatory response and collagen capsule formation, due to its outstanding ability to resist nonspecific protein adsorption. More importantly, when compared with a bare PVC catheter, the pMPCDA coating exhibits outstanding antithrombotic properties when tested in an ex vivo rabbit perfusion model. Thus, it is envisioned that this biomimetic erythrocyte membrane surface strategy will provide a promising way to mitigate inflammation and thrombosis caused by the use of blood-contacting catheters.

High-Performance LiNi0.8Mn0.1Co0.1O2 Cathodes By Atomic-Layer-Deposited Sulfide Coatings

Due to its higher capacity compared to the commercialized LiNixMnyCo1-x-yO2 (NMCs, 0< x, y <1) with lower Ni content (x≤0.6), LiNi0.8Mn0.1Co0.1O2 (NMC811) is now considered as the next promising cathode for lithium-ion batteries (LIBs). However, it still suffers from more serious performance degradation and safety hazard than the commercial ones. These existing issues are reflected as cation mixing, oxygen evolution, irreversible phase-transition, transition metal ion dissolution, and microcracking. Aimed at addressing these problems, surface coating has proven to be an important and effective approach. In recent years, atomic layer deposition (ALD) has emerged as an accurate tool to apply uniform and conformal coatings over NMCs at the atomic level, which have shown remarkable effects on the improved performance of batteries.1-4 Herein, for the first time we deposited ultrathin ALD Li2S coatings5 conformally over NMC811 composite electrodes. It was found that the ALD Li2S coatings enable to enhance performance of NMC811 cathodes with much better cyclability and rate capability. To clarify the effects of the ALD Li2S coatings, we utilized a suite of characterization tools including X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, and transmission X-ray microscopy. The results revealed that the ALD Li2S coatings can perfectly maintain the NMC structure during cycling, thus significantly suppress the crack formation. Furthermore, the Li2S layer can react with and eliminate H2O in electrolyte and O2 released from the NMC structure. In addition, the measurements of electrochemical impedance spectroscopy were applied, which confirms that the Li2S coatings serve as physical protection layers to prevent the interfacial reactions between the NMC cathode and liquid electrolyte. It can be foreseen that sulfides would be a new class of coating materials for addressing issues of NMC cathodes.1. Meng, X.; Yang, X. Q.; Sun, X. L., Advanced Materials 2012, 24 (27), 3589-3615.2. Liu, Y.; Wang, X.; Cai, J.; Han, X.; Geng, D.; Li, J.; Meng, X., Journal of Materials Science & Technology 2020, 54, 77-86.3. Wang, X.; Cai, J.; Liu, Y.; Han, X.; Ren, Y.; Li, J.; Liu, Y.; Meng, X., Nanotechnology 2020, 32 (11), 115401.4. Gao, H.; Cai, J.; Xu, G.-L.; Li, L.; Ren, Y.; Meng, X.; Amine, K.; Chen, Z., Chem. Mater. 2019, 31 (8), 2723-2730.5. Meng, X.; Comstock, D. J.; Fister, T. T.; Elam, J. W., ACS Nano 2014, 8 (10), 10963-10972.

Effects of Processing Time, Mixing Speed, and Mixer on Agglomerates in Fuel Cell Cathode Inks

To prepare a catalyst ink, the large agglomerates of platinum on carbon (Pt/C) powder must be broken down into the primary aggregate particles. This physical process is necessary to form a homogenous mixture that produces uniform and defect-free coatings, as well as maximizing electrochemical performance. Large agglomerates of Pt/C catalyst can limit oxygen diffusion and reduce contact area between ionomer and active Pt area in polymer electrolyte membrane fuel cells (PEMFCs) and electrolyzer catalyst layers. Proper mixing of the catalyst ink before deposition is critical in breaking up these agglomerates, but excessive mixing wastes time and energy and, in some cases, may even damage the catalyst particles.1 There have been several studies of ultrasonication time and energy affecting cathode performance and agglomerate size.1–3 However, there has been considerably less work on mechanical mixing methods, which are more relevant for large-scale manufacturing.This work explores the impact of mixing time and speed on Pt/C agglomerate size using five different mechanical mixers including ball milling and rotor-stator mixers with distinct geometries. Optical micrograph analysis of these rod-coated catalyst layers reveals an exponential decay of particle agglomerates as a function of mixing time, eventually reaching a steady state where there is little to no change in the number of particles over 15 μm in diameter. For a given mixer geometry, mixing speed determines the lowest attainable particle size distribution with higher speeds leading to greater breakup of agglomerate particles (see Figure 1). Rheometry is utilized as a complementary technique to assess the degree of ink mixing completion. Continuous mixing renders higher ink shear viscosity values until plateauing at similar time intervals at which an unvarying particle size distribution is observed. In-situ electrochemical testing of these thin gas diffusion electrodes (GDEs) is employed to correlate the process-driven parameters that govern ink agglomerate size and rheology with fuel cell performance.This research at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE- AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) Advanced Manufacturing Office (AMO).This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Advanced Manufacturing Office. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.(1) Wang, M.; Park, J. H.; Kabir, S.; Neyerlin, K. C.; Kariuki, N. N.; Lv, H.; Stamenkovic, V. R.; Myers, D. J.; Ulsh, M.; Mauger, S. A. Impact of Catalyst Ink Dispersing Methodology on Fuel Cell Performance Using In-Situ X-Ray Scattering. ACS Appl. Energy Mater. 2019, 2 (9), 6417–6427. https://doi.org/10.1021/acsaem.9b01037.(2) Pollet, B. G. Let’s Not Ignore the Ultrasonic Effects on the Preparation of Fuel Cell Materials. Electrocatalysis 2014, 5 (4), 330–343. https://doi.org/10.1007/s12678-014-0211-4.(3) Pollet, B. G. The Use of Ultrasound for the Fabrication of Fuel Cell Materials. Int. J. Hydrog. Energy 2010, 35 (21), 11986–12004. https://doi.org/10.1016/j.ijhydene.2010.08.021.Caption: Figure 1. Plot of number of catalyst agglomerates particles with equivalent diameter larger than 15 µm as a function of rotor-stator rotational speed and time. Figure 1

Stiffness of targeted layer-by-layer nanoparticles impacts elimination half-life, tumor accumulation, and tumor penetration

Nanoparticle (NP) stiffness has been shown to significantly impact circulation time and biodistribution in anticancer drug delivery. In particular, the relationship between particle stiffness and tumor accumulation and penetration in vivo is an important phenomenon to consider in optimizing NP-mediated tumor delivery. Layer-by-layer (LbL) NPs represent a promising class of multifunctional nanoscale drug delivery carriers. However, there has been no demonstration of the versatility of LbL systems in coating systems with different stiffnesses, and little is known about the potential role of LbL NP stiffness in modulating in vivo particle trafficking, although NP modulus has been recently studied for its impact on pharmacokinetics. LbL nanotechnology enables NPs to be functionalized with uniform coatings possessing molecular tumor-targeting properties, independent of the NP core stiffness. Here, we report that the stiffness of LbL NPs is directly influenced by the mechanical properties of its underlying liposomal core, enabling the modulation and optimization of LbL NP stiffness while preserving LbL NP outer layer tumor-targeting and stealth properties. We demonstrate that the stiffness of LbL NPs has a direct impact on NP pharmacokinetics, organ and tumor accumulation, and tumor penetration-with compliant LbL NPs having longer elimination half-life, higher tumor accumulation, and higher tumor penetration. Our findings underscore the importance of NP stiffness as a design parameter in enhancing the delivery of LbL NP formulations.

Growth characteristics and properties of micro-arc oxidation coatings on AlSi10Mg selective laser-melted components

Micro-arc oxidation (MAO) ceramic coatings were prepared on porous AlSi10Mg selective laser-melted components to improve their corrosion property. The microstructure and composition of the coatings at different processing times were characterized via scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. Results showed that the diameter of micro-pores increased with an extension of treatment time, the porosity of coatings decreased from 6.24% to 0.85%. Thickness increased from 4.45 ± 0.01 μm to 15.20 ± 0.01 μm and surface roughness increased from 0.76 ± 0.01 μm to 5.41 ± 0.01 μm with increasing processing time. Meanwhile, the coatings were mostly composed of γ-Al2O3 and trace amounts of α-Al2O3, Al2SiO5, AlPO4 and WO3, the content of α-Al2O3 was increased from 0.51% to 4.12%. Corrosion current density decreased from 2.213 e−5 A·cm−2 to 1.088 e−7 A·cm−2. The polarization resistances Rb were increased from 4.8 × 103 Ω·cm2 to 2.6 × 105 Ω·cm2. The long term EIS results show that Rb was 7.7 × 103 Ω·cm2 after 3 weeks immersion, which show that the MAO coatings could provide good protection on AlSi10Mg alloy. The gas holes and defects of the SLM components were treated via MAO to form uniform MAO coatings on the surface of a sample, expanding the application range of selective laser-melted components in corrosive environments.

Measurement of elastic modulus of laser cladding coatings by laser ultrasonic method

The elastic modulus is an important parameter that can be used to evaluate the properties of laser cladding coatings. However, methods of measuring the elastic modulus are destructive, time consuming, and inefficient. A nondestructive testing method based on a laser ultrasonic is presented. It can be used to measure the elastic modulus, but also to characterise the uniformity of the laser cladding coating. First, the surface microstructure of a laser cladding coating was observed using an optical microscope, and the elastic modulus of the coating was evaluated by a micro-indentation tester. The results showed that large dendrites with a small elastic modulus were mostly distributed in the joints, while the smaller equiaxed grains with a large elastic modulus were mainly distributed in the beads. However, there was no obvious difference between the joint and the bead in the energy spectrum measured by energy dispersive spectroscopy. Second, the surface wave signals were collected on the coating by laser ultrasonic, and the maximum amplitude and the delay time of surface waves of the scanning area were obtained. Through the relationship between the velocity of the surface wave and the elastic modulus, the distribution of the elastic modulus could be measured by a laser ultrasonic C-scan method. Comparison with the micro-indentation results shows that the laser ultrasonic is feasible for measuring the elastic modulus and characterising the uniformity of laser cladding coatings.

Osteoblast Cell Response on Polycrystalline Diamond-Coated Additively Manufactured Scaffolds.

Additive manufacturing of metals using selective laser melting can create customized parts with various degrees of complexity and geometry for medical implants. However, challenges remain in accepting orthopedic implants due to the bio-inert surface of metal scaffolds, resulting in a lack of osseointegration. Here, we show that polycrystalline diamond (PCD) coatings on selective laser melted titanium (SLM-Ti) scaffolds can improve the cell-to-material interaction of osteoblasts. The results show that by controlling the uniformity of the diamond coatings, we can mediate the biological response of osteoblasts, such as cell adhesion, proliferation, and spreading. The osteoblasts show favorable cell adhesion and spreading on non-planar PCD-coated scaffolds compared to the un-coated SLM-Ti scaffold. This study plays an important role in understanding the key physicochemical behavior of bone cell growth on customized orthopedic implant materials.

Microstructure and flow accelerated corrosion resistance of Cr coatings electrodeposited in a trivalent chromium bath

In this study, Cr coatings were electrodeposited on carbon steel substrates by a trivalent Cr salt. The microstructure of the Cr coatings and their flow accelerated corrosion (FAC) resistance in simulated secondary circuit environments (10 MPa and 150 °C) of nuclear power plants were investigated. The results showed that the as-deposited coating was amorphous and crack-free. Annealing at 200 °C resulted in the decrease of Cr (OH) 3 and the increase of Cr and Cr 2 O 3 on the coating surface , which improved the corrosion resistance of the coating. The subsequent FAC test showed that the Cr coatings significantly improved the FAC resistance of the carbon steel substrate. The coating annealed at 200 °C exhibited better FAC resistance. The Cr-rich oxide film formed on the coatings was mainly Cr 2 O 3 , with a small amount of Cr and CrO 2 . Due to the galvanic effects caused by pinhole defects, abnormally grown annular deposits formed on the coating surface. • Uniform and dense Cr coatings were electrodeposited from a trivalent Cr bath. • Annealing at 200 °C reduced Cr(OH) 3 on the coating surface and increased Cr and Cr 2 O 3 . • The Cr-rich oxide film formed in the corrosion was Cr 2 O 3 and a small amount of CrO 2 . • The interface between the coating and the substrate formed Cr-rich corrosion areas.

Correction of thickness uniformity of multilayer fluoride coatings on steep spherical substrates using shadowing mask combinations in planetary rotation systems.

In this study, the deposition angle parameter was introduced into the traditional deposition model to eliminate the coating thickness errors caused by large deposition angles and differences in the microstructures of coatings from the expected values. Based on the different thickness distributions of MgF2 and LaF3 coatings, a method that involves switching shadowing masks and a stepwise numerical optimization algorithm were proposed to control each coating thickness distribution accurately. When designing shadowing masks for a multilayer antireflective (AR) coating with a wide incident angle range, the correlation between the thickness distributions of the MgF2 and LaF3 layers was added to the merit function to ensure consistency in the two distributions. Two-layer deep-ultraviolet (DUV) AR fluoride coatings and a six-layer DUV low-polarization antireflection fluoride coating at 193 nm were fabricated on spherical substrate holders using thermal evaporation. In the experiment, when the ratio of the clear aperture to the radius of curvature was increased from -1.68 to 1.63, the thickness uniformities of the MgF2 and LaF3 layers of the two-layer DUV AR coatings on the fused silica substrates increased to a minimum of 98.49%. Owing to the transmission spectra and the incidence angle-resolved transmission, uniform optical performance and low-variation polarization transmittance were also achieved for the 193 nm AR coating deposited on the fused silica substrates.

Evaluation of the Uniformity of Protective Coatings on Concrete Structure Surfaces Based on Cluster Analysis.

With the continuous development of urbanization and industrialization in the world, concrete is widely used in various engineering constructions as an engineering material. However, the consequent problem of durability of concrete structures is also becoming increasingly prominent. As an important additional measure, a protective coating can effectively improve the durability of concrete performance. Moreover, the uniformity of the concrete surface coating will directly affect its protective effect. Therefore, we propose a nondestructive inspection and evaluation method of coating uniformity based on infrared imaging and cluster analysis for concrete surface coating uniformity detection and evaluation. Based on the obtained infrared images, a series of processing and analysis of the images were carried out using MATLAB software to obtain the characteristics of the infrared images of the concrete surface. Finally, by extracting the temperature distribution data of the pixel points on the concrete surface, an evaluation method of concrete surface coating uniformity based on a combination of cluster analysis and hierarchical analysis was established. The evaluation results show that the determination results obtained by this method are consistent with the actual situation. This study has a positive contribution to the testing of concrete surface coating uniformity and its evaluation.