scholarly journals Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko

Science ◽  
2015 ◽  
Vol 349 (6247) ◽  
pp. aab0464-aab0464 ◽  
Author(s):  
T. Spohn ◽  
J. Knollenberg ◽  
A. J. Ball ◽  
M. Banaszkiewicz ◽  
J. Benkhoff ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal And Mechanical Properties ◽  
Surface Layers ◽  
Near Surface ◽  
Comet 67P

Influence of ion treatment modes on the physical and mechanical properties of zirconia ceramics

2020 ◽  
Vol 10 ◽  
pp. 5-18
Author(s):  
S. А. Ghyngаzоv ◽  
◽  
V. А. Коstеnко ◽  
A. K. Khassenov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Current Density ◽  
Ion Beam ◽  
Physical And Mechanical Properties ◽  
Oxygen Stoichiometry ◽  
Continuous Mode ◽  
Zirconia Ceramics ◽  
Surface Layers ◽  
Near Surface ◽  
Ion Treatment

The article considers the influence of the treatment modes by N2+ and Ar+ ions beams on the physical and mechanical properties of zirconia ceramics. Surface modification of zirconia ceramics was performed using two modes of ion treatment — pulsed and continuous. The pulse mode of treatment by N2+ ions was realized at an accelerating voltage of 250 – 300 kV, current density j = 150 – 200 A/cm2, and energy density W = (3.5 and 5) ± 5 % J/cm2. The continuous mode of treatment by Ar+ ions was realized at an accelerating voltage of 30 kV and an ion current density of 300 and 500 μA/cm2. The fluence of the Ar+ ion beam varied from 1016 to 1018 cm–2. It is established that the pulsed mode of ion treatment leads to the melting and recrystallization of the surface of ceramics. It is shown that this treatment leads to a violation of the oxygen stoichiometry in ceramics and, as a result, there is an appearance of electrical conductivity in the near-surface layers, the layers of zirconia ceramics become conductive. It was established that the continuous mode of ion treatment does not lead to the melting and recrystallization of the ceramics surface, but is accompanied by its slight etching. It is shown that under the action of continuous ion treatment, microhardness increases (by 14 %). Hardening of the surface layers of ceramics is observed at a depth that exceeds the average projected range of Ar+ ion by 103 times.

Physico-mechanical properties and micromechanisms of local deformation in thin near-surface layers of complex multiphase materials

2017 ◽  
Vol 81 (3) ◽  
pp. 360-364 ◽  
Author(s):  
Y. I. Golovin ◽  
A. I. Tyurin ◽  
S. D. Victorov ◽  
A. N. Kochanov ◽  
A. A. Samodurov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Local Deformation ◽  
Surface Layers ◽  
Near Surface ◽  
Multiphase Materials

Effect of Titanium Implantation on the Mechanical Properties of Silicon Nitride

1994 ◽  
Vol 354 ◽  
Author(s):  
T. Fujihana ◽  
O. Nishimura ◽  
K. Yabe ◽  
H. Hayashi ◽  
M. Iwaki
Keyword(s):  
Mechanical Properties ◽  
Friction Coefficient ◽  
Room Temperature ◽  
Surface Hardness ◽  
Atomic Fraction ◽  
Metallic State ◽  
Wear Properties ◽  
Surface Layers ◽  
Near Surface ◽  
Projected Range

AbstractA study has been made of the chemical composition and mechanical properties of Ti+-implanted Si3N4 surface layers. Implantation of 48Ti+ was performed with doses ranging from 10 to 1017 ions cm”2 at an energy of 150 keV, and at nearly room temperature. XPS was used to analyze the depth dependence of atomic fraction and chemical bonding states of Ti+-implanted layers. The near-surface hardness was measured by a Vickers hardness tester. The friction and wear properties were measured under unlubricated conditions at room temperature using a pin on disk-plane and a block on wheel-periphery configurations, in which the pin and wheel used were AISI1045 and ASTM Wl-9, respectively. Implanted Ti-atoms formed a gaussian distribution predicted by the range theory. At the average projected range, most of Ti-atoms existed as a metallic state and TiN bonding was also formed. Oxygen and carbon were found near the surface layers. In addition to the surface peak, O-atoms accumulated in front of the average projected range of Ti. Such O-atoms formed bonds of Si-oxides and Ti-oxides. Carbon existed as a graphitic state. With increasing a Ti dose, the near-surface hardness decreased, and the wear rate increased at the running-in stage having the high friction coefficient. The steady wear attributed to the stable friction coefficient appeared after the running-in stage, although such a stable stage was not observed for unimplanted Si3N4. The mechanism for the change in mechanical properties of Si3N4 induced by Ti+-implantation will be discussed in relation to XPS characteristics.

Evaluating Micromechanical Properties at Surfaces Using Nanoindentation With Finite-Element Modeling

2002 ◽  
Author(s):  
J. A. Knapp ◽  
D. M. Follstaedt ◽  
S. M. Myers
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Finite Element Modeling ◽  
Mechanical Damage ◽  
Surface Region ◽  
Small Scale ◽  
Surface Layers ◽  
Near Surface ◽  
Element Modeling ◽  
Surface Modified

Detailed finite-element modeling of nanoindentation data is used to obtain accurate mechanical properties of very thin films or surface-modified layers independently of the properties of the underlying substrates. These procedures accurately deduce the yield strength, elastic modulus, and layer hardness, and greatly increase the usefulness of indentation testing with very thin surface layers. Moreover, extraction of the effective Young’s modulus in the near surface region should enable mechanical damage studies on a small scale. This paper presents a brief overview of the procedures involved and illustrates them with He-implanted Ni.

Lappability of end gauges and mechanical properties of their near-surface layers

1986 ◽  
Vol 29 (7) ◽  
pp. 621-624
Author(s):  
G. B. Kainer ◽  
V. M. Kuchumova ◽  
L. A. Kochanova ◽  
V. I. Savenko ◽  
N. P. Fedoseeva ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Layers ◽  
Near Surface ◽  
End Gauges

Researching structure heterogeneity of VT41 titanium alloy billet after thermomechanical treatment

2019 ◽  
pp. 36-46 ◽  
Author(s):  
P. N. Medvedev ◽  
S. A. Naprienko ◽  
O. S. Kashapov ◽  
A. S. Shpagin ◽  
I. P. Popov
Keyword(s):  
Mechanical Properties ◽  
Vickers Microhardness ◽  
Structural Components ◽  
Surface Layers ◽  
Near Surface ◽  
Surface Areas ◽  
Β Phase ◽  
Α Phase ◽  
Central Regions ◽  
Structure Heterogeneity

The heterogeneity of the titanium VT41 structural state after hot upset test was investigated by analytical methods of optical and scanning microscopy. Vickers microhardness measurements were performed to estimate the mechanical properties. The analysis of the distribution of deformation and the features of the formation of the structural components of the specimen. Globular grains were deformed by the mechanism of intergranular slipping. β-grains and α-plates made the greatest contribution to plastic deformation. Lamellar grains of α-phase in the zone of localization of deformation undergo recrystallization. The dimensions of the zone in which the recrystallization occurred, coincide with the zone of localization of the deformation, estimated by macrostructure. When tempering the billet, the β-phase in the center of the sample breaks down into α-plates, and in the near-surface areas into smaller grains, probably representing needle-like β-titanium martensite. A decrease in microhardness in the central regions may be due both to recrystallization and to the fact that martensite has been quenched in the surface layers. 

Phase Composition and Mechanical Properties Modification in Cr/Ti System by Short-Pulsed High Intensity Ion Beams Treatment

2015 ◽  
Vol 756 ◽  
pp. 319-324 ◽  
Author(s):  
V.I. Shymanski ◽  
G.E. Remnev ◽  
S.K. Pavlov ◽  
V.V. Uglov
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Phase Composition ◽  
Titanium Carbide ◽  
High Intensity ◽  
Ion Beams ◽  
Surface Alloys ◽  
Surface Layers ◽  
Near Surface ◽  
Structure Phase

In the present the results of research of structure, phase composition and microhardness measurement of the surface layers of the Cr/Ti system treated by short-pulsed high intensity ion beams (HPIB) are presented. It was shown that the HPIB impact on a “coating/substrate” system can serve as an affective way to produce near-surface alloys in the metals. In particular, in the Cr/Ti system the formation of solid solution β-Ti (Cr) as well as titanium carbide TiCx was revealed. The found changes in structure and phase composition of titanium caused by the HPIB impact allow to increase its microhardness in 2 times.

scholarly journals Optimizationof Process Parameters of Copper Composites Produced via Friction Stir Processing

2018 ◽  
Vol 6 (01) ◽  
Author(s):  
B N V S K Ganesh Gupta K ◽  
BD Santha Rao
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Processing ◽  
Optical Microscope ◽  
Surface Layers ◽  
Near Surface ◽  
Engineering Research ◽  
Friction Stir ◽  
Surface Composites ◽  
New Material ◽  
Tib2 Particles

Increasing demands for operating properties of fabricated elements on one hand, and a necessity of reducing mass of a structure on the other, triggers materials engineering research into producing surface layers representing required functional properties. Methods commonly used in the production of surface layers, such as surfacing, spraying or re-melting with a laser beam have been known for years. A new method is the friction stir processing (FSP) of surface layers. The FSP process is primarily used for the modification of microstructure in near-surface layers of processed metallic components this deformation is produced by forcibly inserting a non-consumable tool into the workpiece, and revolving the tool in a stirring motion as it is pushed laterally through the workpiece. This is promising process for the automotive and aerospace industries where new material will need to be developed to improve resistance to wear, creep, and fatigue. The main objective of this project is to be producing copper reinforced metal matrix composite layers using micro sized TiB2 particles via friction stir processing (FSP) in order to enhance surface mechanical properties. Taguchi method was used to optimize these factors for maximizing the mechanical properties of surface composites. The fabricated surface composites were examined by optical microscope (OM) and scanning electron microscopy (SEM) for dispersion reinforcement particles. It was found that TiB2 particles are uniformly dispersed in the stir zone. Mechanical properties like tensile, Impact, hardness, were also evaluated. The results showed that functional characteristics of surface composites increased with the increase in vol. % of the micro sized TiB2 reinforcement particles. The observed mechanical properties are correlated with microstructure and fracture features.

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