scholarly journals Evolution of the microstructure, residual stresses, and mechanical properties of W–Si–N coatings after thermal annealing

2005 ◽  
Vol 20 (5) ◽  
pp. 1356-1368 ◽  
Author(s):  
A. Cavaleiro ◽  
A.P. Marques ◽  
J.V. Fernandes ◽  
N.J.M. Carvalho ◽  
J.Th. De Hosson
Keyword(s):  
Residual Stress ◽  
Thermal Annealing ◽  
Amorphous Film ◽  
Amorphous Coating ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Composition Structure ◽  
The One ◽  
Deposited Film

W–Si–N films were deposited by reactive sputtering in a Ar + N2 atmosphere from a W target encrusted with different number of Si pieces and followed by a thermal annealing at increasing temperatures up to 900 °C. Three iron-based substrates with different thermal expansion coefficients, in the range of 1.5 × 10−6 to 18 × 10−6 K−1 were used. The chemical composition, structure, residual stress, hardness (H), and Young’s modulus (E) were evaluated after all the annealing steps. The as-deposited film with low N and Si contents was crystalline whereas the one with higher contents was amorphous. After thermal annealing at 900 °C the amorphous film crystallized as body-centered cubic α–W. The crystalline as-deposited film presented the same phase even after annealing. There were no significant changes in the properties of both films up to 800 °C annealing. However, at 900 °C, a strong decrease and increase in the hardness were observed for the crystalline and amorphous films, respectively. It was possible to find a good correlation between the residual stress and the hardness of the films. In several cases, particularly for the amorphous coating, H/E higher than 0.1 was reached, which envisages good tribological behavior. The two methods (curvature and x-ray diffraction) used for calculation of the residual stress of the coatings showed fairly good agreement in the results.

Residual Stress in Two Dental Alloys During Porcelain Application

1987 ◽  
Vol 31 ◽  
pp. 255-260
Author(s):  
M. Bagby ◽  
SJ Marshall ◽  
GW Marshall
Keyword(s):  
Residual Stress ◽  
Thermal Expansion ◽  
Residual Stresses ◽  
Casting Process ◽  
Dental Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Dental Restorations ◽  
Expansion Coefficients

Residual stresses in dental castings are widely held to be the cause of distortion and change of fit in ceramic bonded to metal dental restorations. Residual stresses are thought to result from the casting process and from ceramic/metal mismatch of thermal expansion coefficients. Such stresses have not been confirmed experimentally. The purpose of this study was to measure residual stress with x-ray diffraction at the various porcelain application steps for two noble dental alloys with two dental opaque porcelains.

The crystal structure and thermal expansion of the CCl4 adduct of Dianin's compound

1990 ◽  
Vol 68 (8) ◽  
pp. 1352-1356 ◽  
Author(s):  
Walter Abriel ◽  
André Du Bois ◽  
Marek Zakrzewski ◽  
Mary Anne White
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Dianin's Compound

The crystal structure of the title compound has been determined by single crystal X-ray diffraction data collected at 293 K, and refined to a final Rw of 0.057. The crystals are rhombohedral, space group [Formula: see text], with a = 27.134(8) Å, c = 10.933(2) Å, and Z = 18. The mole ratio of Dianin's compound (4-p-hydroxyphenyl-2,2,4-trimethylchroman) to CCl4 is 6:1. The guest molecules are disordered. X-ray powder diffraction was carried out in the temperature range from 10 to 300 K. From this, the thermal expansion coefficients for the a- and c-axes and the volume have been determined. Keywords: thermal expansion, crystal structure, clathrate.

Structure and Thermal Expansion Behavior of Dy2-xGdxMo4O15 Solid Solution

2008 ◽  
Vol 368-372 ◽  
pp. 1665-1667
Author(s):  
M.M. Wu ◽  
X.L. Xiao ◽  
Y.Z. Cheng ◽  
J. Peng ◽  
D.F. Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Thermal Expansion ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Coefficients ◽  
Cell Volumes

A new series of solid solutions Dy2-xGdxMo4O15 (x = 0.0-0.9) were prepared. These compounds all crystallize in monoclinic structure with space group P21/c. The lattice parameters a, b, c and unit cell volumes V increase almost linearly with increasing gadolinium content. The intrinsic thermal expansion coefficients of Dy2-xGdxMo4O15 (x = 0.0 and 0.25) were obtained in the temperature range of 25 to 500°C with high-temperature X-ray diffraction. The correlation between thermal expansion and crystal structure was discussed.

scholarly journals An examination of the thermal expansion of urea using high-resolution variable-temperature X-ray powder diffraction

2005 ◽  
Vol 38 (6) ◽  
pp. 1038-1039 ◽  
Author(s):  
Robert Hammond ◽  
Klimentina Pencheva ◽  
Kevin J. Roberts ◽  
Patricia Mougin ◽  
Derek Wilkinson
Keyword(s):  
Thermal Expansion ◽  
High Resolution ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
Polymorphic Transformations ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Cell Dimensions ◽  
Expansion Coefficients ◽  
Unit Cell Dimensions

Variable-temperature high-resolution capillary-mode powder X-ray diffraction is used to assess changes in unit-cell dimensions as a function of temperature over the range 188–328 K. No evidence was found for any polymorphic transformations over this temperature range and thermal expansion coefficients for urea were found to be αa= (5.27 ± 0.26) × 10−5 K−1and αc= (1.14 ± 0.057) × 10−5 K−1.

A temperature-dependent structure study of gem-quality hibonite from Myanmar

2010 ◽  
Vol 74 (5) ◽  
pp. 871-885 ◽  
Author(s):  
M. Nagashima ◽  
T. Armbruster ◽  
T. Hainschwang
Keyword(s):  
Room Temperature ◽  
Structure Study ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Trigonal Bipyramidal ◽  
Expansion Coefficients ◽  
Increasing Temperature ◽  
Length Distortion

AbstractThe structure of hibonite from Myanmar (space group P63/mmc, Z = 2, at room temperature a = 5.5909(1), c = 21.9893(4) Å), with simplified formula CaAl12O19 and composition (Ca0.99Na0.01)Σ1.00 was investigated between temperatures of 100 K and 923 K by single-crystal X-ray diffraction methods. Structure refinements have been performed at 100, 296, 473 and 923 K. In hibonite from Myanmar, Ti substitutes for Al mainly at the octahedral Al4 site and, to a lesser degree, at the trigonal bipyramidal site, Al2. The Al4 octahedra build face-sharing dimers. If Ti4+ substitutes at Al4, adjacent cations repulse each other for electrostatic reasons, leading to off-centre cation displacement associated with significant bond-length distortion compared to synthetic (Ti-free) CaAl12O19. Most Mg and smaller proportions of Zn and Si are assigned to the tetrahedral Al3 site. 12-coordinated Ca in hibonite replaces oxygen in a closest-packed layer. However, Ca is actually too small for this site and engages in a ‘rattling-type’ motion with increasing temperature. For this reason, Ca does not significantly increase thermal expansion coefficients of hibonite. The expansion of natural Ti,Mg-rich hibonite between 296 and 923 K along the x and the z axes is αa = 7.64×10–6 K–1 and αc = 11.19×10–6 K–1, respectively, and is thus very similar to isotypic, synthetic CaAl12O19 and LaMgAl11O19 (LMA).

Highly Bioactive Porous Composite Scaffolds of Bovine Hydroxyapatite (BHA-Ti, BHA-TiO2, BHA-Li2O)

2007 ◽  
Vol 330-332 ◽  
pp. 411-414 ◽  
Author(s):  
Faik N. Oktar ◽  
Simeon Agathopoulos ◽  
Gultekin Goller ◽  
H. Gökçe ◽  
E.S. Kayali ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Correct Selection ◽  
Porous Scaffolds ◽  
High Porosity ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
Commercial Sugar ◽  
Expansion Coefficients ◽  
Porosity Measurements ◽  
Selection Of

Porous scaffolds of hydroxyapatite (HA), derived from calcined bovine bones and doped with various reinforcing materials, such as Ti, TiO2 and Li2O, were produced with the aid of commercial sugar, which was added as 20 wt% with respect to the total batch, and sintering at 1200°C and 1300°C. The samples were characterized by SEM and X-ray diffraction analysis as well as by porosity measurements. The experimental results showed that porosity can be controlled by the correct selection of doping materials. The optimum sintering temperature was 1200°C since firing at 1300°C caused extended sintering and thus porosity was considerably reduced. Matching of chemical nature as well as thermal expansion coefficients between HA and the doping components are of high importance for the structural integrity of the resultant scaffolds. Doping with Li2CO3 seemed to have the highest potential for achieving high porosity, likely due to the decomposition to Li2O, but the amount of Li2CO3 used should not jeopardizing HA bioactivity. The use of natural sugar is an economic way of producing safe for the health porous HA scaffolds.

Crystal structure and thermal expansion of hexakis(phenylthio)benzene and its CBr4 clathrate

1995 ◽  
Vol 73 (4) ◽  
pp. 513-521 ◽  
Author(s):  
Darek Michalski ◽  
Mary Anne White ◽  
Pradip K. Bakshi ◽  
T. Stanley Cameron ◽  
Ian Swainson
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Neutron Powder Diffraction ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

The crystal structures of hexakis(phenylthio)benzene (HPTB) and its CBr4 clathrate have been determined by single crystal X-ray diffraction data collected at T = 18 °C and refined to final Rw of 0.036 and 0.047, respectively. Pure HPTB is triclinic, space group [Formula: see text] (No. 2), with a = 9.589(2) Å, b = 10.256(1) Å, c = 10.645(2) Å, α = 68.42(1)°, β = 76.92(2)°, γ = 65.52(1)°, and Z = 1. The CBr4 clathrate of HPTB is rhombohedral, space group [Formula: see text] (No. 148), with a = 14.327(4) Å, b = 20.666(8) Å, and Z = 3. The host–guest mole ratio of HPTB–CBr4 is 1:2. Neutron powder diffraction was carried out on powders of both compounds in the temperature range 25 K < T < 295 K. Thermal expansion coefficients were determined for HPTB and HPTB–CBr4 over this temperature range. Keywords: thermal expansion, crystal structure, clathrate.

scholarly journals Термическое расширение и люминесцентные свойства триортогерманатов CaLa-=SUB=-2-x-=/SUB=-Eu-=SUB=-x-=/SUB=-Ge-=SUB=-3-=/SUB=-O-=SUB=-10-=/SUB=- (x=0.0-0.6)

2018 ◽  
Vol 60 (2) ◽  
pp. 363
Author(s):  
O.А. Липина ◽  
Л.Л. Сурат ◽  
Я.В. Бакланова ◽  
И.Ф. Бергер ◽  
А.П. Тютюнник ◽  
...  
Keyword(s):  
Linear Thermal Expansion ◽  
Excitation Wavelength ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
Strain Anisotropy ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
First Time ◽  
Luminescence Characteristics

AbstractSolid solutions CaLa_2- x Eu_ x Ge_3O_10 ( x = 0.0–0.6, Δ x = 0.1) have been synthesized for the first time. The compounds are isostructural to CaLa_2Ge_3O_10, they crystallize in the monoclinic system, space group P 2_1/ c , Z = 4. The low-temperature X-ray diffraction studies have revealed the strain anisotropy of germanate CaLa_2Ge_3O_10 crystal lattice in the temperature range 80–298 K, and the linear thermal expansion coefficients have been calculated. The optical properties of the activated phases have been studied, and the influence of the dopant concentration and the excitation wavelength on the luminescence characteristics of the synthesized compounds has been established.

Mechanical and Thermal Properties of MgAl2O4-Y3Al5O12 Ceramic Composites

2018 ◽  
Vol 281 ◽  
pp. 255-260 ◽  
Author(s):  
Jiang Bo Liu ◽  
Zhou Fu Wang ◽  
Hao Liu ◽  
Xi Tang Wang ◽  
Yan Ma
Keyword(s):  
Thermal Properties ◽  
Raw Materials ◽  
Laser Flash ◽  
Ceramic Composites ◽  
Mechanical And Thermal Properties ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Increasing Temperature ◽  
Flash Diffusivity

MgAl2O4-Y3Al5O12 ceramic composites were prepared using fused spinel and a Y2O3 micropowder as the raw materials. The microstructure and thermal properties of the composites were characterized by X-ray diffraction, scanning electron microscopy, laser flash diffusivity measurements. The mechanical properties were also determined. MgAl2O4-Y3Al5O12 ceramic composites are composed of spinel and garnet structures. The thermal expansion coefficients of MgAl2O4 and MgAl2O4-Y3Al5O12 ceramics are similar. The measured thermal diffusivity decreases gradually with increasing temperature. Thermal conductivity of the composites is in the range of 3.3-5.8 W∙m-1∙K-1 from 400°C to 900°C.

Behaviors of the Zr–1.0Sn–0.39Nb–0.31Fe–0.05Cr Alloy at High Temperature

2011 ◽  
Vol 399-401 ◽  
pp. 80-84
Author(s):  
Yi Yuan Tang ◽  
Jie Li Meng ◽  
Kai Lian Huang ◽  
Jian Lie Liang
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
High Temperature ◽  
Oxide Film ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thin Oxide Film ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Phase transformation of the Zr-1.0Sn-0.39Nb-0.31Fe-0.05Cr alloy was investigated by high temperature X-ray diffraction (XRD). The XRD results revealed that the alloy contained two precipitates at room temperature, namely β-Nb and hexagonal Zr(Nb,Fe,Cr,)2. β-Nb was suggested to dissolve into the α-Zr matrix at the 580oC. Thin oxide film formed at the alloy’s surface was identified as mixture of the monoclinic Zr0.93O2and tetragonal ZrO2, when the temperature reached to 750oC and 850 oC. The thermal expansion coefficients of αZr in this alloy was of αa = 8.39×10-6/°C, αc = 2.48×10-6/°C.

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