Thermal physical processes during forming of biocompatible Ca-P coatings by detonation spraying

Carbon-carbon composites with calcium phosphate (Ca-P) coatings (with a thickness up to of ≈100 μm) are considering as prospective grafts for defect bone substitution. Detonation spraying of Ca-P layers allows to fulfil a deposition mode with relative low temperature loads (up to a temperature of the processed surface of ≈850…1100 K) under a pulsed pressure of ≈2…6 bar. Such deposition conditions could promote to minimal thermal decomposition of feedstock HAp.

Determining the Optimal Mode of the Inconel 718 Alloy Deposition at a Direct Laser Deposition Plant

The paper describes determining the optimal direct laser deposition mode when processing the results of a two-factor experiment by the steep ascent method. The dependence of the ultimate tensile strength on the volumetric energy density and the lateral pitch was chosen as the target function.

Active sites for ice nucleation differ depending on nucleation mode

The nucleation of ice crystals in clouds is poorly understood, despite being of critical importance for our planet’s climate. Nucleation occurs largely at rare “active sites” present on airborne particles such as mineral dust, but the nucleation pathway is distinct under different meteorological conditions. These give rise to two key nucleation pathways where a particle is either immersed in a supercooled liquid water droplet (immersion freezing mode) or suspended in a supersaturated vapor (deposition mode). However, it is unclear if the same active sites are responsible for nucleation in these two modes. Here, we directly compare the sites that are active in these two modes by performing immersion freezing and deposition experiments on the same thin sections of two atmospherically important minerals (feldspar and quartz). For both substrates, we confirm that nucleation is dominated by a limited number of sites and show that there is little correlation between the two sets of sites operating in each experimental method: across both materials, only six out of 73 sites active for immersion freezing nucleation were also active for deposition nucleation. Clearly, different properties determine the activity of nucleation sites for each mode, and we use the pore condensation and freezing concept to argue that effective deposition sites have size and/or geometry requirements not of relevance to effective immersion freezing sites. Hence, the ability to nucleate is pathway dependent, and the mode of nucleation has to be explicitly considered when applying experimental data in cloud models.

Электроосаждение металлов на p-Si из водных электролитов

The features of electrochemical deposition of metal coatings on hole silicon are presented, and the properties of the obtained metal layers are measured. The dependence of the thickness of the depleted region and the internal voltage drop in it on the composition of the electrolyte and the type of precipitated metal was investigated. The effect of current density and electrolyte composition on the properties of precipitation is proved. By selection of the electrolyte pretreatment and the deposition mode, metal precipitates with acceptable adhesion and low longitudinal resistance were obtained.

Influence of the nature of monomer on electropolymerization processes and physical and chemical properties of films based on hydroxy-substituted tetraphenylporphyrins

The ability to oxidatively polymerization from a solution in ethanol of tetraphenylporphyrin derivatives: 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin, 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin, Zn-5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin, Zn-5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin were studied. The polymerization of 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin does not occur; three of the four studied porphyrins form thin transparent polyporphyrin films tightly adhered to the electrodes surface. The influence of the nature of the monomer, the deposition mode, and the supporting electrolyte used on the process of electropolymerization and the properties of the deposited polyporphyrin films were studied. The spectral changes observed during the deposition of the films indicate that the generation of the polyporphyrin films occurs through the formation of C–O–C bonds and the keep of the porphyrin macroheterocycle in polyporphyrin.

Energy Spectrum CT Differential Diagnosis of Idiopathic Calcification and Ossification of Adult Intervertebral Disc: A Report of three Cases

BackgroundCalcification of adult intervertebral disc is a rare clinical disease, and its imaging diagnosis directly affects the formulation of the operation plan. In this study, three cases are used to illustrate that the application of energy spectrum CT as the preoperative diagnosis can better reflect the pathological situation and structure of the focus, further helping with preoperative judgment. Case presentationWe report two cases of idiopathic calcification of adult thoracic intervertebral disc. In addition to Routine CT and MRI before the operation, energy spectrum CT was taken to produce analytical diagnosis of the lesions. According to the results, the surgical resection mode was determined. The postoperative confirmation was highly consistent with the image diagnosis. Likewise, a case of posterior margin of vertebral body and ossification of intervertebral disc was selected for the same diagnosis procedure, and the two were compared for differentiation.ConclusionIn the illustration that the texture of the vertebral canal presser being uncertain, the energy spectrum can identify the calcium type of the presser, as well as the atomic number histogram being able to fix the absolute content value and the distribution rule of calcium. Meanwhile, the calcium-water astigmatism map can resolve the calcium deposition mode, with better estimation of the focus presser hardness.

Electrochemical deposition of nanocrystalline Ni–W coatings from citrate electrolytes

In this paper, requirements for wear-resistant coatings of Ni–40%W manufactured by electrochemical deposition are determined, and the electrolyte stability is studied. The influence of temperature and current density on the deposition of the Ni–W alloy from a citrate electrolyte was researched, and the optimal deposition mode was found. The maximum operating time of the electrolyte is established by the dependence of the current efficiency for the Ni–W alloy on the electric power transmission. The necessity of using membrane electrolyzers during the deposition of nickel-tungsten coatings is substantiated.

Structure and properties of chromium-based nanostructured coatings deposited by magnetron sputtering

Technological capabilities of a magnetron sputtering vacuum installation equipped with an ion source for preliminary treatment of the substrate surface with argon ions are considered. The adhesive strength and corrosion resistance of chromium-based nanostructured coatings produced by magnetron sputtering were studied. It was found that deposited chromium coatings have a high corrosion resistance in solutions of nitric and hydrofluoric acid. With an increase in the thickness of nanostructured coatings, its corrosion resistance increases significantly: in a coating with a thickness of <1 μm, the number of corrosion points (pores in the coating) was 5-10 times greater than in a coating with a thickness of 2.3-2.5 μm. With the help of electron microscopy, the surface morphology and size distribution of nanoparticles in the structure of chromium coatings have been investigated. Depending on the deposition mode, the coating consists of crystallites with sizes from 45 to 200 nm.