Low Pressure Homoepitaxial Growth of 4H-SiC on 4°off-Axis Substrates

2015 ◽  
Vol 821-823 ◽  
pp. 181-184 ◽  
Author(s):  
Ji Chao Hu ◽  
Yu Ming Zhang ◽  
Ren Xu Jia ◽  
Yue Hu Wang ◽  
Bin Xin
Keyword(s):  
Surface Roughness ◽  
Low Pressure ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
Growth Pressure ◽  
Step Bunching ◽  
Homoepitaxial Growth ◽  
Surface Mobility ◽  
The Impact

Step-bunching and triangular defects are significant problems in achieving higher growth rate 4H-SiC epilayers in a horizontal hot wall CVD reactor using a standard non-chlorinated chemistry of silane-propane-hydrogen on 4°off-axis substrates. In this work, the impact of growth pressure on generation of step-bunching and triangular defects and the correlations between the surface roughness and the formation of defects were investigated. It has been found that the impact of growth pressure on concentration of the triangle defects and surface roughness is obviously different. An overall reduction of defects was observed with decreasing growth pressure while the surface roughness increased. The increased adatom surface mobility in low pressure range and minimization of surface free energy are the main reasons for the phenomenon above. High Resolution X-Ray Diffraction (HRXRD) indicated that the structural quality of 4H-SiC epilayers performed at low pressure was higher than that obtained at high pressure.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

scholarly journals Rated definition of degree of cutter coating influence upon parameters of surface layer quality of parts worked

2017 ◽  
Vol 2 (7) ◽  
pp. 20-24
Author(s):  
Вячеслав Безъязычный ◽  
Vyacheslav Bezyazychnyy ◽  
Максим Басков ◽  
Maksim Baskov
Keyword(s):  
Surface Roughness ◽  
Surface Layer ◽  
Residual Stresses ◽  
Layer Surface ◽  
Wear Resistant Coatings ◽  
Cutter Wear ◽  
Definition Of ◽  
Surface Layer Quality ◽  
The Impact

The impact of cutter wear-resistant coatings upon cutting process parameters and characteristics of surface layer quality in the parts worked: residual stresses, a degree and a depth of work hardening of a surface layer, surface roughness is investigated.

scholarly journals Исследование этапов превращения кремния в карбид кремния в процессе атомного замещения методами полного внешнего отражения рентгеновских лучей и рентгеновской дифрактомерии

2022 ◽  
Vol 64 (3) ◽  
pp. 326
Author(s):  
С.А. Кукушкин ◽  
А.В. Осипов ◽  
Е.В. Осипова ◽  
В.М. Стожаров
Keyword(s):  
Structural Quality ◽  
Total External Reflection ◽  
X Rays ◽  
Reflection Method ◽  
X Ray Diffraction ◽  
Modified Technique ◽  
Substitution Method ◽  
X Ray ◽  
Sic Films

X-ray diffraction and total external reflection of X-rays (X-ray reflectometry) methods were used to study the successive stages of synthesis of epitaxial SiC films on Si (100) X-ray diffraction and total external X-ray reflection (XRD) methods were used to study successive stages of synthesis of epitaxial SiC films on Si (100) surfaces, (110) and (111) surfaces by the atom substitution method. The data on the transformation evolution of (100) surfaces were studied, (110) and (111) Si, into SiC surfaces. A comparative analysis of the X-ray structural quality of the SiC layers grown on Si by the atom substitution method with the quality of SiC layers grown by Advanced Epi by the standard CVD method. A modified technique for the total outer X-ray reflection method, based on measurements of the intensity of the reflected X-rays using a special parabolic mirror. It is shown that the method of total external reflection method makes it possible to obtain important information about the degree of surface roughness of SiC layers, the evolution of their crystal structure and plasmon energy in the process of Si to SiC conversion.

scholarly journals The Impact of Slicing Softwares on the Mechanical Properties of 3D Printed Parts

2020 ◽  
Vol 9 (2) ◽  
pp. 487-494
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
3D Printer ◽  
Stl File ◽  
3D Printed ◽  
Intersection Curves ◽  
The Impact

“Slicing tool” or “Slicing Software” computes the intersection curves of models and slicing planes. They improve the quality of the model being printed when given in the form of STL file. Upon analyzing a specimen that has been printed using two different slicing tools, there was a drastic variation on account of the mechanical properties of the specimen. The ultimate tensile strength and the surface roughness of the material vary from one tool to another. This paper reports an investigation and analysis of the variation in the ultimate tensile strength and the surface roughness of the specimen, given that the 3D printer and the model being printed is the same, with a variation of usage of slicing software. This analysis includes ReplicatorG, Flashprint as the two different slicing tools that are used for slicing of the model. The variation in the ultimate tensile strength and the surface roughness are measured and represented statistically through graphs. An appropriate decisive conclusion was drawn on the basis of the observations and analysis of the experiment on relevance to the behavior and mechanical properties of the specimen.

scholarly journals Tentative Exploration of Bacterial Concrete with Partial Replacement of Stone Dust

2019 ◽  
Vol 8 (4) ◽  
pp. 3610-3615
Keyword(s):  
Liberal Arts ◽  
Positive Impact ◽  
Partial Replacement ◽  
X Ray Diffraction ◽  
Stone Dust ◽  
Scale Breaking ◽  
The Right ◽  
The Impact ◽  
3D Shapes

Concrete remains the foremost magnificently used artifact on the soil. The vulnerability of concrete to very little scale breaking decreases its quality and toughness. The repair steel onself for splits is pricey, time disbursement and gets to be arduous in blocked off regions. A self mending bioremediation procedure consolidating spar quick microorganism has been projected among the show take into consideration which could operate the arrangement to this issue. The being spar precipitation will naturally recuperate the smaller scale splits and pores inside the concrete and avoid the broadening of splits. this could cause the thrifty of costs and times went through for maintenance and avoid the subsequent misfortune in quality and solidness of concrete. The concentration of true bacteria Megatherium 10^5cfu/ml and salt were introduced in auxiliary concrete to comprehend the right concentration of microbes. the quality of the foremost elevated review of being concrete had progressed as compared to the foremost reduced review due to the classification of the component. The cogitate has been created to assess the impact on mechanical and toughness properties of M35 review concrete created with substitution of cement with quarry clean ( third,15%,20% and, twenty five and 30%) for each set mechanical property wear examined by liberal arts compression check for 3d shapes, flexural check for bars at that quality ar progressing to be reached thereon result able to embrace the true bacteria Megaterum and at the instant another time discover out the compression take a look at for 3d shapes, flexural check for bars. being spar precipitation was evaluated utilizing associate X-ray diffraction investigation visualized by filtering research and analyzed by vitality dispersive spectroscope. it had been found that the right concentration of B.megaterium had a positive impact on quality auxiliary concrete.

scholarly journals Impact of Structural Defects on the Surface Quality of Hardwood Species Sliced Veneers

2020 ◽  
Vol 10 (18) ◽  
pp. 6265
Author(s):  
Vasiliki Kamperidou ◽  
Efstratios Aidinidis ◽  
Ioannis Barboutis
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Wood Species ◽  
Research Work ◽  
Structural Defects ◽  
Material Surface ◽  
Typical Structure ◽  
Hardwood Species ◽  
The Impact

The surface roughness constitutes one of the most critical properties of wood and wood veneers for their extended utilization, affecting the bonding ability of the veneers with one another in the manufacturing of wood composites, the finishing, coating and preservation processes, and the appearance and texture of the material surface. In this research work, logs of five significant European hardwood species (oak, chestnut, ash, poplar, cherry) of Balkan origin were sliced into decorative veneers. Their surface roughness was examined by applying a stylus tracing method, on typical wood structure areas of each wood species, as well as around the areas of wood defects (knots, decay, annual rings irregularities, etc.), to compare them and assess the impact of the defects on the surface quality of veneers. The chestnut veneers presented the smoothest surfaces, while ash veneers, despite the higher density, recorded the highest roughness. In most of the cases, the roughness was found to be significantly lower around the defects, compared to the typical structure surfaces, probably due to lower porosity, higher density and the presence of tensile wood. The results reveal that the presence of defects does not affect the roughness of the veneers and increases neither the processing requirements of the veneer sheets before finishing, nor the respective production cost of veneers and the veneer-based wood panels. The high utilization prospects of the examined wood species in veneer production, even those bearing various defects, is highlighted.

scholarly journals Surface Roughness Investigation of Poly-Jet 3D Printing

Mathematics ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1758
Author(s):  
Nectarios Vidakis ◽  
Markos Petousis ◽  
Nikolaos Vaxevanidis ◽  
John Kechagias
Keyword(s):  
Surface Roughness ◽  
3D Printing ◽  
Surface Quality ◽  
Back Propagation ◽  
Physical Models ◽  
Layer By Layer ◽  
Linear Regression Models ◽  
Feed Forward Back Propagation ◽  
The Impact

An experimental investigation of the surface quality of the Poly-Jet 3D printing (PJ-3DP) process is presented. PJ-3DP is an additive manufacturing process, which uses jetted photopolymer droplets, which are immediately cured with ultraviolet lamps, to build physical models, layer-by-layer. This method is fast and accurate due to the mechanism it uses for the deposition of layers as well as the 16 microns of layer thickness used. Τo characterize the surface quality of PJ-3DP printed parts, an experiment was designed and the results were analyzed to identify the impact of the deposition angle and blade mechanism motion onto the surface roughness. First, linear regression models were extracted for the prediction of surface quality parameters, such as the average surface roughness (Ra) and the total height of the profile (Rt) in the X and Y directions. Then, a Feed Forward Back Propagation Neural Network (FFBP-NN) was proposed for increasing the prediction performance of the surface roughness parameters Ra and Rt. These two models were compared with the reported ones in the literature; it was revealed that both performed better, leading to more accurate surface roughness predictions, whilst the NN model resulted in the best predictions, in particular for the Ra parameter.

Structural and Magnetic Properties of Co50 ± x Pt50 ± x Thin Films Prepared by Mbe Co-Evaporation on (001) MgO Substrate at Various Temperatures

1998 ◽  
Vol 517 ◽  
Author(s):  
V. Parasote ◽  
M.-C. Cadevwlle ◽  
V. Pierron-Bohnes ◽  
W. Grange
Keyword(s):  
Magnetic Properties ◽  
Linear Increase ◽  
Anisotropy Energy ◽  
Structural Quality ◽  
Main Peak ◽  
X Ray Diffraction ◽  
Thermally Activated ◽  
Theoretical Predictions ◽  
Structural And Magnetic Properties

AbstractStructural and magnetic properties of Co50 ± x Pt50± x films 25-50 nm thick, prepared by molecular beam epitaxy onto a Pt buffer grown on MgO (001) substrate have been investigated. A series of 3 samples with different compositions (x = 6, 0, -6) was grown at 800 K on a 10 nm thick Pt buffer and another series of 5 samples of equiatomic composition was prepared at various growth temperatures (390 K≤ TG≤ 780 K) on a Pt buffer 4 nm thick. X-ray diffraction and TEM studies show the presence of grains with [111] and [002] orientations, the [002] grains being a mixture of the tetragonal L10 ordered phase and of the fcc disordered one. Both the thickness of the buffer layer and the deposition temperature are determinant parameters of the structural quality of the films and of the degree of long range order (LRO). An apparent LRO parameter (ηapp) is deduced from the superstructure and main peak intensity ratio. Its increase with the growth temperature is described through a thermally activated model that yields a small activation energy of 0.28 eV, illustrating the role played by both surface diffusion and surface interactions in building the L10 compound in agreement with theoretical predictions. An average uniaxial magnetocrystalline anisotropy energy (Kuav) is deduced from the magnetization curves measured by a SQUID. The anisotropy energy of the [002] grains (Ku002) is deduced, assuming a linear relationship between the anisotropies and the phase percentages. One observes a continuous but not linear increase of Ku002 with ηapp.

Study of the structural quality of heteroepitaxial silicon-on-sapphire structures by high-resolution X-ray diffraction, X-ray reflectivity, and electron microscopy

2014 ◽  
Vol 59 (3) ◽  
pp. 315-322 ◽  
Author(s):  
A. E. Blagov ◽  
A. L. Vasiliev ◽  
A. S. Golubeva ◽  
I. A. Ivanov ◽  
O. A. Kondratev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
X Ray

Analysis of Fracture Process and Common Defects in Casting Alloys EN43100 Manufactured by Die Casting Technology

2014 ◽  
Vol 1077 ◽  
pp. 39-43
Author(s):  
Stefan Gaspar ◽  
Ján Pasko
Keyword(s):  
Airline Industry ◽  
Fracture Process ◽  
Die Casting ◽  
Structural Quality ◽  
Quality Properties ◽  
Casting Technology ◽  
Casting Alloys ◽  
The Impact ◽  
Casting Production

Recent research in the process of die casting production of aluminium alloys which are nowadays deeply implemented in the rapidly developing automobile, shipping and airline industry aims to increase the manufacture and quality properties of the casting in order to obtain its high mechanical properties at acceptable economic costs. In terms of ensuring the quality indicators in the production of aluminium castings it is necessary to pay close attention to internal structural quality of the castings characterized by type and extent of foundry defects (cavities, Al2O3 particles, internal cold laps). The presenting contribution deals with the analysis of the fracture process, the microorganism disturbance of test samples, the impact of casting speed on the occurrence and extent of the castings porosity and reasons for the internal foundry defects of casting alloys EN 43100 manufactured by die casting technology.

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