Selective Laser Fusion of Titanium Based Gradient Alloy Reinforced by Nano Sized TiC Ceramic

2018 ◽  
Vol 916 ◽  
pp. 85-90 ◽  
Author(s):  
Igor Shishkovsky ◽  
Vladimir Scherbakov
Keyword(s):  
Titanium Substrate ◽  
Laser Fusion ◽  
Formation Mechanisms ◽  
Additive Process ◽  
Chemical Segregation ◽  
Selective Laser Fusion ◽  
The Difference ◽  
Carbide Particles ◽  
Nano Size ◽  
Surface Improvement

The surface improvement of light-weighted metals by adding of hard ceramic particles into a metal matrix has promised to be perspectives for aerospace industry. In the present study, titanium carbides of nano size were incorporated to the titanium substrate by a selective laser melting (SLM) of Ti + (10, 15 and 20 wt.%) TiC powder mixtures via an Ytterbium fiber laser with 1.075 mm wavelength. Optimal regimes of the 3D laser additive process were determined. We studied how the interfacial properties would change due to the difference in composition in case of the titanium matrix nano composites (TMNC) reinforced with carbides. The phase analysis of the fabricated TMNC showed that the initial carbide particles are dissolved after the remelting with different velocities. A particular attention was paid to the carbide dilution and secondary carbides formation mechanisms when the TiC was mixed with titanium. Various parameters, such as microstructure, phase constitution and mechanical properties of the gradient TMNCs were investigated by means of OM, SEM, XRD and microhardness measurement. It was shown that the microstructure had two types of heterogeneity: the TiC particles at the interlayer interfaces and element chemical segregation on the boundaries of the tracks.

TEM investigations of surface residual stress relaxation in A12O3 and Al2O3-SiC nanocomposite

1994 ◽  
Vol 52 ◽  
pp. 628-629
Author(s):  
J. Fang ◽  
H. M. Chan ◽  
M. P. Harmer
Keyword(s):  
Residual Stress ◽  
Single Phase ◽  
Stress Relief ◽  
Stress Recovery ◽  
Surface Residual Stress ◽  
Microscopic Mechanism ◽  
Sic Particles ◽  
Annealing Procedure ◽  
The Difference ◽  
Nano Size

It was Niihara et al. who first discovered that the fracture strength of Al2O3 can be increased by incorporating as little as 5 vol.% of nano-size SiC particles (>1000 MPa), and that the strength would be improved further by a simple annealing procedure (>1500 MPa). This discovery has stimulated intense interest on Al2O3/SiC nanocomposites. Recent indentation studies by Fang et al. have shown that residual stress relief was more difficult in the nanocomposite than in pure Al2O3. In the present work, TEM was employed to investigate the microscopic mechanism(s) for the difference in the residual stress recovery in these two materials.Bulk samples of hot-pressed single phase Al2O3, and Al2O3 containing 5 vol.% 0.15 μm SiC particles were simultaneously polished with 15 μm diamond compound. Each sample was cut into two pieces, one of which was subsequently annealed at 1300° for 2 hours in flowing argon. Disks of 3 mm in diameter were cut from bulk samples.

scholarly journals Quantum Chemistry Estimation of Adhesion Strength of Hydroxyapatite with Titanium Substrate

2021 ◽  
Vol 03 (04) ◽  
pp. 1-1
Author(s):  
Alla V. Balueva ◽  
◽  
Ilia N. Dashevskiy ◽  
Patricia Todebush ◽  
◽  
...  
Keyword(s):  
Adhesion Strength ◽  
Density Functional ◽  
Reaction Path ◽  
Titanium Substrate ◽  
Reaction Products ◽  
Functional Theory ◽  
Standard Material ◽  
The Difference ◽  
Ground Energy ◽  
Biocompatible Coatings

One of the ways to improve the fusion of an implant with bone tissue is through the use of biocompatible coatings, in particular, hydroxyapatite (HAp). It is important to assess the strength of the HAp adhesion to the implant. The measure of the strength of the bond of the coating with the substrate is the energy of this bond. Using density functional theory and molecular dynamics, the reaction path, reaction products, oscillation frequency, activation energy and bond energy between different combinations of component anions HAp and Ti (II) – the standard material of implants – are calculated. Using the computational chemistry software suite Gaussian 09 (Revision C.01 was used), the stable configurations of the reactants and products are found, and the binding energy of hydroxyapatite and titanium is then calculated based on the difference in ground energy of reactants and ground energy of products. Thus, the method of adhesion strength estimation between HAp coatings and Ti is proposed based on numerical calculations using MD software, and suggestions are provided on which conditions would be the best for optimal binding strength.

On the difference of aerosol hygroscopicity between high and low RH environment in the North China Plain

2021 ◽  
Author(s):  
Jingnan Shi ◽  
Juan Hong ◽  
Nan Ma ◽  
Qingwei Luo ◽  
Hanbing Xu ◽  
...  
Keyword(s):  
Chemical Composition ◽  
North China Plain ◽  
North China ◽  
Experimental Period ◽  
Formation Mechanisms ◽  
Large Contribution ◽  
The North ◽  
The North China Plain ◽  
The Difference ◽  
Aerosol Hygroscopicity

<p>Simultaneous measurements of aerosol hygroscopicity and chemical composition were performed at a suburban site in the North China Plain in winter 2018 using a self-assembled hygroscopic tandem differential mobility analyzer (H-TDMA) and a capture-vaporizer time-of-flight aerosol chemical speciation monitor (CV-ToF-ACSM), respectively. During the experimental period, aerosol particles usually show an external mixture in terms of hygroscopicity, with a less hygroscopic particles mode (LH) and a more hygroscopic mode (MH). The average ensemble mean hygroscopicity parameter (κ<sub>mean</sub>) are 0.16, 0.18, 0.16, and 0.15 for 60, 100, 150, and 200 nm particles, respectively. Two episodes with different RH/T conditions and secondary aerosol formations are distinguished. Higher aerosol hygroscopicity is observed for all measured sizes in the high RH episode (HRH) than in the low RH episode (LRH). In LRH, κ decreases as the particle size increases, which may be explained by the large contribution of non- or less-hygroscopic primary compounds in large particles due to the enhanced domestic heating emissions at low temperature. The number fraction of LH mode at 200 nm even exceeds 50%. Closure analysis is carried out between the HTDMA-measured κ and the ACSM-derived hygroscopicity using different approximations for the hygroscopic parameters of organic compounds (κ<sub>org</sub>). The results indicate that κ<sub>org</sub> is less sensitive towards the variation of its oxidation level under HRH conditions but has a stronger O: C-dependency under LRH conditions. The difference in the chemical composition and their corresponding physical properties under different RH/T conditions reflects potentially different formation mechanisms of secondary organic aerosols at those two distinct episodes.</p>

Bainite

2015 ◽  
pp. 99-112
Keyword(s):  
Solute Drag ◽  
Lower Bainite ◽  
Transformation Product ◽  
Intermediate Temperature ◽  
Bainitic Transformation ◽  
Formation Mechanisms ◽  
Temperature Transformation ◽  
The Difference

Bainite is an intermediate temperature transformation product of austenite. This chapter describes the conditions under which bainite is likely to form. It discusses the effects of alloying on bainitic transformation, the difference between upper and lower bainite, and the influence of solute drag on bainite formation mechanisms. It also discusses the development of ferrite-carbide bainites and their effect on toughness, hardness, and ductility.

scholarly journals Study on the Origin and Fluid Identification of Low-Resistance Gas Reservoirs

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhou Yuhui ◽  
Hu Qingxiong ◽  
Liu Wentao ◽  
Wu Zhiqi ◽  
Yan Yule ◽  
...  
Keyword(s):  
Technical Problem ◽  
Laboratory Data ◽  
Gas Content ◽  
Formation Mechanisms ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Fluid Identification ◽  
Low Resistance ◽  
Neutron Porosity ◽  
The Difference

The Wu 2 section of the Ke017 well block is a low-resistance gas reservoir with ultralow porosity and low permeability. The comprehensive analysis of rock lithology, physical properties, sedimentary characteristics, and gas content demonstrated that the development of micropores in illite/smectite dominated clay minerals together with the resulted additional conductivity capability and complex reservoir pore structures, as well as the enrichment of self-generating conductivity minerals like zeolites and pyrite which were the formation mechanisms of low-resistance gas layers in the Wu 2 section. A low-resistance gas reservoir has poor physical property, and it is difficult to distinguish the oil layer from the dry, gas, or water layers. In this paper, based on well/mud logging data and laboratory data, by taking advantages of the “excavation effect” of neutron gas and the dual-lateral resistivity difference between different depths, we successfully established a set of low-contrast log response methods for the identification and evaluation of oil layer and formation fluids. For a gas layer, the difference between neutron porosity and acoustic (or density) porosity is smaller than 0 and the difference in dual-lateral resistivity is greater than 0. For a water layer, the neutron porosity is similar to the acoustic (or density) porosity and the dual-lateral resistivity difference will be less than 0. While for a dry layer or a layer with both gas and water, the difference in porosity as well as dual-lateral resistivity is very small. The proposed method effectively solves the technical problem of oil layer and formation fluid identification in low-resistance gas reservoirs.

scholarly journals Examination of Adsorption Orientation of Amyloidogenic Peptides Over Nano-Gold Colloidal Particle Surfaces

2019 ◽  
Vol 20 (21) ◽  
pp. 5354 ◽  
Author(s):  
Kazushige Yokoyama ◽  
Kieran Brown ◽  
Peter Shevlin ◽  
Jack Jenkins ◽  
Elizabeth D’Ambrosio ◽  
...  
Keyword(s):  
Charge Distribution ◽  
Size Dependence ◽  
Partial Charge ◽  
Gold Colloid ◽  
Gold Colloids ◽  
Nano Gold ◽  
Secondary Layer ◽  
Amyloidogenic Peptides ◽  
The Difference ◽  
Nano Size

The adsorption of amyloidogenic peptides, amyloid beta 1–40 (Aβ1–40), alpha-synuclein (α-syn), and beta 2 microglobulin (β2m), was attempted over the surface of nano-gold colloidal particles, ranging from d = 10 to 100 nm in diameter (d). The spectroscopic inspection between pH 2 and pH 12 successfully extracted the critical pH point (pHo) at which the color change of the amyloidogenic peptide-coated nano-gold colloids occurred due to aggregation of the nano-gold colloids. The change in surface property caused by the degree of peptide coverage was hypothesized to reflect the ΔpHo, which is the difference in pHo between bare gold colloids and peptide coated gold colloids. The coverage ratio (Θ) for all amyloidogenic peptides over gold colloid of different sizes was extracted by assuming Θ = 0 at ΔpHo = 0. Remarkably, Θ was found to have a nano-gold colloidal size dependence, however, this nano-size dependence was not simply correlated with d. The geometric analysis and simulation of reproducing Θ was conducted by assuming a prolate shape of all amyloidogenic peptides. The simulation concluded that a spiking-out orientation of a prolate was required in order to reproduce the extracted Θ. The involvement of a secondary layer was suggested; this secondary layer was considered to be due to the networking of the peptides. An extracted average distance of networking between adjacent gold colloids supports the binding of peptides as if they are “entangled” and enclosed in an interfacial distance that was found to be approximately 2 nm. The complex nano-size dependence of Θ was explained by available spacing between adjacent prolates. When the secondary layer was formed, Aβ1–40 and α-syn possessed a higher affinity to a partially negative nano-gold colloidal surface. However, β2m peptides tend to interact with each other. This difference was explained by the difference in partial charge distribution over a monomer. Both Aβ1–40 and α-syn are considered to have a partial charge (especially δ+) distribution centering around the prolate axis. The β2m, however, possesses a distorted charge distribution. For a lower Θ (i.e., Θ <0.5), a prolate was assumed to conduct a gyration motion, maintaining the spiking-out orientation to fill in the unoccupied space with a tilting angle ranging between 5° and 58° depending on the nano-scale and peptide coated to the gold colloid.

THEORETICAL STUDIES ON THE FORMATION MECHANISM AND STRUCTURE OF PENTAFULVENONE AND AZAFULVENONE

2008 ◽  
Vol 07 (02) ◽  
pp. 233-246 ◽  
Author(s):  
XIU-MEI PAN ◽  
XIU-JUAN JIA ◽  
YING LIU ◽  
HAO SUN ◽  
ZHONG-MIN SU ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Potential Energy Surfaces ◽  
Vibrational Mode ◽  
Formation Mechanisms ◽  
Ortho Position ◽  
Elimination Reaction ◽  
Diazo Ketone ◽  
The Difference ◽  
Energy Surfaces ◽  
Mode Assignment

The formation mechanisms of pentafulvenone and azafulvenone were extensively investigated at the B3LYP/6-311++G** level and the potential energy surfaces were drawn out. Ketene pentafulvenone (A) and 3-carbonyl-3H-pyrrole (C) can be formed by eliminating N 2 from the diazo ketone via α elimination reaction and ketene 2-carbonyl-2H-pyrrole (B), 4-carbonyl-4H-imidazole (D), and 2-carbonyl-2H-imidazole (E) were formed by the elimination of water or methanol from pyrrole-2-carboxylic acid (rB) and carboxylate (rD and rE) via β elimination reaction. The structures of these monomers were compared and showed some information about the bond changed characters. The structure investigation indicated that the C = C bond is activated when the nitrogen atom locates in the ortho position of the C = C = O part, and therefore ortho-monomers are more facile to react. The difference of the amount and stability of the corresponding dimers are caused by differing the position and number of nitrogen atom and the variety of the ortho-dimer is complicated. In addition, the infrared spectra of the title species were also analyzed including the vibrational frequencies, IR relative intensities, and vibrational mode assignment.

Surface Improvement by Overlapping in Multipass FSP

2012 ◽  
Vol 730-732 ◽  
pp. 865-870
Author(s):  
João Gandra ◽  
Rosa M. Miranda ◽  
Pedro Vilaça
Keyword(s):  
Metal Working ◽  
Friction Stir ◽  
Median Size ◽  
Local Modification ◽  
Hardness Increase ◽  
Surface Reinforcement ◽  
Silicon Carbide Particles ◽  
And Control ◽  
Carbide Particles ◽  
Surface Improvement

Friction stir processing (FSP) is an emerging metal-working technique based on the same fundaments as friction stir welding that allows local modification and control of microstructures, for the purpose of improving surface or in-volume mechanical properties. This paper aims to explore several applications of the FSP technology for surface improvement either by multipass FSP or surface reinforcement with silicon carbide particles. An AA5083-H111 alloy 8 mm thick was tested. Structural and mechanical differences were observed when overlapping by the advancing side (AS) direction or by the retreating side (RS) one. Hardness within the processed layer increased by 8.5 % and was seen to be approximately constant between passes. Toughness under bending was improved by 18 %. The production of particle-reinforced metal matrix composite materials (MMC) was investigated, as the severe plastic deformation inherent to the process promoted the dispersion of 12.5 μm median size SiC particles, resulting in a severe superficial hardness increase.

Development of Hydroxyapatite Thin Film on Titanium Substrate by Electrophoretic Deposition

2005 ◽  
Vol 284-286 ◽  
pp. 901-904 ◽  
Author(s):  
Chang Kuk You ◽  
Xian Wei Meng ◽  
Tae Yub Kwon ◽  
Yu Zhong Yang ◽  
J.L. Ong ◽  
...  
Keyword(s):  
Electrophoretic Deposition ◽  
Coating Thickness ◽  
Applied Voltage ◽  
Counter Electrode ◽  
Coating Layer ◽  
Sol Gel ◽  
Titanium Substrate ◽  
Powder Concentration ◽  
Ha Coating ◽  
Nano Size

Electrophoretic deposition was used for HA coating on dental implants with different coating thickness. The HA coating thickness was examined in terms of applied voltage and time, and powder concentration in suspension. Nano-size HA and SiO2-CaO-P2O5-B2O3 bioglass powders were synthesized by sol-gel method. Polyvinyl alcohol (3 wt%) as a binder was resolved in ethyl alcohol, then, nano HA powder was dispersed ultrasonically in the mixture for 15 min and pH was adjusted with HNO3 for positive charging on particle. Titanium substrate was held on cathode and counter electrode was platinum. HA with 0.5 % and 0.03 % of powder concentration was deposited electrophoretically at 10~20 V for 1~20 minutes. The thickness of as-deposited HA layer decreased from nearly 80 µm (0.5 %, 20 V, 10 min) to 4~5 µm (0.03%, 10V, 1 min) as powder concentration, applied voltage and time decreased, respectively. The surface of HA coating layer deposited in lower powder concentration showed much more homogeneous and relatively dense morphology, in contrast, the surface in thick suspension became rough or porous and was easily spalled. In a co-deposition of HA and bioglass, co-deposited glass played an important role in increasing bonding strength between coating layer and substrate. It is believed that electrophoretic deposition method can be one of alternatives for relatively thin and easy HA coating.

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