Friction and cohesion between single crystals of copper

1952 ◽  
Vol 212 (1111) ◽  
pp. 464-467 ◽  
Keyword(s):  
Single Crystals ◽  
Static Friction ◽  
The Other ◽  
Flat Surfaces

Friction and adhesion experiments have been carried out between two large crystals of copper of controlled orientation from the surface of which all oxide had been removed. One crystal was in the form of a sphere and the other was a sphere with two flat surfaces cut parallel to particular planes. The coefficient of dry static friction between two (100) faces was greater than one hundred and between (111) faces was approximately twenty-five. The greater value for the (100) faces was attributed to the greater digging-in and the increased area of contact produced by slip as displacement occurred. Similar cohesion experiments showed that bonds were formed of the same strength as the parent metals. The rupture of the bond formed between crystals and the slip of the metal adjacent to the bond were studied.

2D Color-Intensity Representation of Ultrasonic Thickness Gauge Measurements

2020 ◽  
pp. 1192-1198
Author(s):  
M.S. Mohammad ◽  
Tibebe Tesfaye ◽  
Kim Ki-Seong
Keyword(s):  
Cost Effective ◽  
The Other ◽  
Thickness Gauge ◽  
Color Intensity ◽  
Digital Readout ◽  
Flat Surfaces ◽  
Video Cameras ◽  
Wide Range ◽  
Cost Effective Alternative ◽  
Ultrasonic Thickness

Ultrasonic thickness gauges are easy to operate and reliable, and can be used to measure a wide range of thicknesses and inspect all engineering materials. Supplementing the simple ultrasonic thickness gauges that present results in either a digital readout or as an A-scan with systems that enable correlating the measured values to their positions on the inspected surface to produce a two-dimensional (2D) thickness representation can extend their benefits and provide a cost-effective alternative to expensive advanced C-scan machines. In previous work, the authors introduced a system for the positioning and mapping of the values measured by the ultrasonic thickness gauges and flaw detectors (Tesfaye et al. 2019). The system is an alternative to the systems that use mechanical scanners, encoders, and sophisticated UT machines. It used a camera to record the probe’s movement and a projected laser grid obtained by a laser pattern generator to locate the probe on the inspected surface. In this paper, a novel system is proposed to be applied to flat surfaces, in addition to overcoming the other limitations posed due to the use of the laser projection. The proposed system uses two video cameras, one to monitor the probe’s movement on the inspected surface and the other to capture the corresponding digital readout of the thickness gauge. The acquired images of the probe’s position and thickness gauge readout are processed to plot the measured data in a 2D color-coded map. The system is meant to be simpler and more effective than the previous development.

On Slip Inception and Static Friction for Smooth Dry Contact

2014 ◽  
Vol 81 (12) ◽  
Author(s):  
Xi Shi
Keyword(s):  
Shear Strength ◽  
Contact Area ◽  
Material Properties ◽  
Static Friction ◽  
Friction Model ◽  
Interfacial Bonding ◽  
The Other ◽  
Material Failure ◽  
Bonding Failure ◽  
Dry Contact

Slip inception mechanism is very important for modeling of static friction and understanding of some experimental observations of friction. In this work, slip inception was treated as a local competence of interfacial bonding failure and weaker material failure. At any contacting point, if bond shear strength is weaker than softer material shear strength, slip inception is governed by interfacial bonding failure. Otherwise, it is governed by softer material failure. Considering the possible co-existence of these two slip inception mechanisms during presliding, a hybrid static friction model for smooth dry contact was proposed, which indicates that the static friction consists of two components: one contributed by contact area where bonding failure is dominant and the other contributed by contact area where material failure is dominant. With the proposed static friction model, the effects of contact pressure, the material properties, and the contact geometry on static friction were discussed.

scholarly journals An enquiry concerning the nature of heat, and the mode of its communication

1832 ◽  
Vol 1 ◽  
pp. 139-147
Keyword(s):  
Principal Part ◽  
Cylindrical Vessel ◽  
The Other ◽  
Metallic Surface ◽  
Previous Trial ◽  
Flat Surfaces ◽  
Different Temperatures ◽  
The One ◽  
Quantity Of Heat

The importance of the investigation here entered into,—inasmuch as it applies to most of the operations of nature as well as art,—appears so manifest, that we shall not recapitulate what the author advances on that subject. Before he proceeds to the detail of his experiments for the purpose of computing the emissions of heat from various bodies under a variety of circumstances, he finds it necessary to premise a minute description of the principal part of the apparatus he contrived for his purpose. This instrument consists of a hollow cylindrical vessel of brass, four inches long, and as many in diameter. It is closed at both ends; but has at one end a cylindrical neck about eight-tenths of an inch in diameter, by which it is occasionally filled with water of different temperatures, and through which also a thermometer, constructed for the purpose, is occasionally introduced, in order to ascertain the changes of temperature in the fluid. As it was in the first instance only meant to observe the quantity of heat that escapes through the sides of the vessel, two boxes were contrived, filled and covered with non-conducting substances, such as eiderdown, fur, &c., which were fitted to the two ends or flat surfaces of the cylinder. Six of these instruments, with proper stands, and auxiliary implements of obvious construction, were prepared for the sake of comparative experiments. A previous trial was made with two of the cylinders, the vertical polished sides of the one being naked, and those of the other covered with one thickness of fine white Irish linen, strained over the metallic surface. Here it was found, contrary to expectation, that in a certain space of time the covered cylinder had lost considerably more heat than the naked one.

Die Kristallstruktur des Lithium-Benzamidinats {Li3[C6H5 - C(NSiMe3)2]3 · NC - C6H5} / The Crystal Structure of the Lithium Phenylamidinate {Li3[C6H5 - C(NSiMe3)2]3 · NC - C6H5}

1994 ◽  
Vol 49 (10) ◽  
pp. 1444-1447 ◽  
Author(s):  
Helmut Goesmann ◽  
Dieter Fenske
Keyword(s):  
Crystal Structure ◽  
Nitrogen Atom ◽  
Single Crystals ◽  
Title Compound ◽  
The Other ◽  
Space Group ◽  
Structure Solution

AbstractSingle crystals of the title compound have been prepared by the reaction of benzonitrile with LiN-(SiMe3)2 in hexane and subsequent evaporation of the solvent. Space group P21/n, Z = 4, structure solution with 7945 observed unique reflections. R = 0.052. Lattice dimensions at -70 °C: a = 1485.2(9); b = 2486.9(11); c = 1568.9(8) pm; β = 91.06(4)°. The compound forms a trimeric ion ensemble in which two of the lithium cations are coordinated by three nitrogen atoms of two phenylamidinate an ions, the other one by four nitrogen atoms of two chelating phenylaminidate anions and in addition by the nitrogen atom of a benzonitrile molecule.

scholarly journals Twinning in Czochralski-Grown 36°-RY LiTaO3 Single Crystals

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1009
Author(s):  
Yutaka Ohno ◽  
Yuta Kubouchi ◽  
Hideto Yoshida ◽  
Toshio Kochiya ◽  
Tomio Kajigaya
Keyword(s):  
Single Crystals ◽  
Slip Plane ◽  
Edge Dislocation ◽  
Lithium Tantalate ◽  
Initiation Site ◽  
The Other ◽  
Burgers Vector ◽  
Partial Dislocations ◽  
Dislocation Arrays ◽  
Extension Direction

The origin of twinning during the Czochralski (CZ) growth of 36°-RY lithium tantalate (LiTaO3) single crystals is examined, and it is shown that lineages composed of dislocation arrays act as an initiation site for twinning. Two types of lineages expand roughly along three different {12¯10} planes and two different {11¯00} planes. The former lineages and some latter lineages are composed of two types of mixed-dislocations with different Burgers vectors, while the other lineages are composed of only one type of edge-dislocation. All the dislocations have the Burgers vector of ⟨12¯10⟩ type with the compression side at the +Z side. Twin lamellae on {101¯2} are generated at a lineage during the CZ growth. We have hypothesized that dislocations in the lineage with b = 1/3⟨12¯10⟩ change their extension direction along a slip plane of {101¯2}, and they dissociate into pairs of partial dislocations with b = 1/6⟨22¯01⟩and 1/6⟨02¯21¯⟩ forming twin lamellae on {101¯2}.

scholarly journals A Technique for Producing Strain-Free Flat Surfaces on Single Crystals of Ice

1970 ◽  
Vol 9 (57) ◽  
pp. 385-390 ◽  
Author(s):  
T. M Tobin ◽  
K. Itagaki
Keyword(s):  
Dislocation Density ◽  
Single Crystals ◽  
Aluminum Surface ◽  
Ice Crystal ◽  
X Ray ◽  
Flat Surfaces ◽  
Etch Pit

The top surface of an accurately aligned ice crystal is melted by an aluminum surface and then frozen to a warm “Lucite” plate ant! tapped free. Etch-pit development shows that the dislocation density on the resulting surface is similar to die bulk dislocation density determined by X-ray topographic methods.

Enhanced Piezoelectric Properties of Piezoelectric Single Crystals by Domain Engineering

2003 ◽  
Vol 785 ◽  
Author(s):  
Satoshi Wada ◽  
Koichi Yako ◽  
Hirofumi Kakemoto ◽  
Takaaki Tsurumi
Keyword(s):  
Single Crystals ◽  
Domain Structure ◽  
Room Temperature ◽  
Piezoelectric Properties ◽  
Domain Size ◽  
Domain Engineering ◽  
The Other ◽  
Domain Structures ◽  
Domain Configuration ◽  
Fine Domain

ABSTRACTFor tetragonal barium titanate (BaTiO3) single crystals, an electric field (E-field) applied along [111]c direction can induce an engineered domain configuration. In this study, the engineered domain structures with different domain sizes were induced into BaTiO3 single crystals, and their piezoelectric properties were investigated as a function of a domain size. Prior to this study, the dependence of domain configuration on the temperature and the E-field was investigated using a polarizing microscope in order to understand the optimum condition for fine and coarse domain structures. As a result, above Curie temperature (Tc) of 132.2 °C, when the E-field over 6 kV/cm was applied along [111]c direction, the engineered domain configuration with fine domain structure appeared. Moreover, it was also found that this fine domain structure was still stable at room temperature without E-field. On the other hand, the coarse domain structure was obtained by poling at just below Tc. Finally, the piezoelectric properties were measured using the 31 resonators with different kinds of domain sizes. As the result, it was found that the piezoelectric properties such as d31 and k31 increased significantly with decreasing domain sizes.

scholarly journals Thermally and Mechanically Induced Regelation of Ice

1985 ◽  
Vol 6 ◽  
pp. 135-137
Author(s):  
Kaoru Horiguchi ◽  
R. D. Miller
Keyword(s):  
Rigid Body ◽  
Supercooled Water ◽  
Static Friction ◽  
The Other ◽  
Wall Boundary

At temperatures slightly below 0°C, ice filling a smooth-walled chamber that has porous phase barriers at either end can move through the chamber in a process resembling regelation; supercooled water passes through one barrier and freezes at the same time that ice melts at the other, emerging through the second barrier as supercooled water. The process may be induced mechanically (by differential water pressures at the phase barriers) or thermally {by imposed temperature differentials). The ice moves as a rigid body with slippage at the ice-wall boundary of the chamber. An apparent coefficient of static friction can be deduced and appeared to be about 0.12 for ice at a machined nylon wall at about -0.04 ˚C.

Ca10V5.2Fe0.8O24, a Novel Oxometalate with Discrete Complex Anions

2003 ◽  
Vol 58 (11) ◽  
pp. 1112-1116 ◽  
Author(s):  
Kurt O. Kleppa ◽  
Norbert A. Harringer ◽  
Hubert Preßlinger
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Bond Distance ◽  
Structure Type ◽  
The Other ◽  
Nominal Composition ◽  
Average Bond ◽  
Complex Anions ◽  
Trigonal Prismatic ◽  
Discrete Complex

Abstract Lustrous needle shaped prismatic single crystals of the new compound Ca10V5.2Fe0.8O24 were obtained out of a sample with nominal composition Ca2Fe1.6V0.4O5 prepared at 1400 °C. The crystals are opaque and stable to humid air. Ca10V5.2Fe0.8O24 crystallizes with a new structure type, space group Pnma with a = 6.803(3), b = 16.015(8), c = 10.418(7)Å , Z = 2, R = 0.041. The crystal structure is characterized by two mononuclear tetrahedral species, MO4, which differ significantly from each other with respect to their M-O bond lengths. One with an average bond distance of 1.709(8)Å represents an orthovanadate ion. The other with a significantly larger value d(M-O) = 1.744(6) Å corresponds to a mixed occupation of its centre according to [V0.8Fe0.2O4]3.5−. In the crystal structure the complex anions are arranged in separate sheets parallel to the (010) plane. They are separated from each other by three crystallographically independent Ca2+ ions which are each coordinated by 7 oxygen atoms in distorted pentagonal bipyramidal and trigonal prismatic configurations, respectively.

Quaternäre Strontium-Kupfer(I)-Lanthanoid(III)-Selenide mit Cer und Praseodym: SrCuCeSe3 und SrCuPrSe3, ein ungleiches Geschwisterpaar / Quaternary Strontium Copper(I) Lanthanoid(III) Selenides with Cerium and Praseodymium: SrCuCeSe3 and SrCuPrSe3, Unequal Brother and Sister

2004 ◽  
Vol 59 (9) ◽  
pp. 985-991 ◽  
Author(s):  
Sabine Strobel ◽  
Thomas Schleid
Keyword(s):  
Single Crystals ◽  
Coordination Number ◽  
Unit Cell ◽  
Structural Relationship ◽  
The Other ◽  
Space Group ◽  
Lattice Constants ◽  
The Third ◽  
Other Hand ◽  
Third Dimension

Quaternary strontium copper(I) lanthanoid(III) selenides are formed by the oxidation of elemental strontium, copper and the corresponding lanthanoid with selenium. Orange to red needle-shaped single crystals of SrCuPrSe3 and SrCuCeSe3 have been synthesized by heating mixtures of Sr, Cu, Pr / Ce and Se with CsI as a flux in evacuated silica tubes to 800°C for 7 d. Both compounds crystallize orthorhombically in space group Pnma with four formula units per unit cell, but with unlike lattice constants (a = 1097.32(6), b = 416.51(2), c = 1349.64(8) pm for SrCuPrSe3 and a = 846.13(5), b = 421.69(2), c = 1663.42(9) pm for SrCuCeSe3) and therefore different structure types. The Pr3+ cations in SrCuPrSe3 are surrounded octahedrally by six Se2− anions forming chains of edge-sharing [PrSe6]9− octahedra that are joined by common vertices. Together with [CuSe4]7− tetrahedra they form [CuPrSe3]2− layers piled up parallel (001). Between those layers the Sr2+ cations are coordinated by seven Se2− anions in the shape of capped trigonal prisms linking the structure in the third dimension. On the other hand in SrCuCeSe3 the Ce3+ cations as well as the Sr2+ cations adopt a coordination number of seven. Since the bonding distances between cerium and selenium match with those of strontium and selenium the two crystallographically independent sites of these cations are occupied statistically by Ce3+ and Sr2+ with equal ratios. Nevertheless, there is a close structural relationship between SrCuPrSe3 and SrCuCeSe3. Similar to SrCuPrSe3 where Cu+ and Pr3+ cations together with Se2− anions form [CuPrSe3]2− layers parallel (001), the Cu+ cations and [(Ce1/Sr1)Se7]11.5− polyhedra in SrCuCeSe3 build strongly puckered layers which are connected by (Ce2)3+/(Sr2)2+ cations. The copper selenium part in both compounds correlates as well, with [CuSe4]7− tetrahedra linked by common vertices to form [CuSe3]5− chains running along [010].

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