Functional surface layers in relaxor ferroelectrics

2020 ◽  
Vol 8 (23) ◽  
pp. 7663-7671
Author(s):  
Nitish Kumar ◽  
Scarlet Kong ◽  
Pankaj Sharma ◽  
Xi Shi ◽  
Gaurav Vats ◽  
...  

We demonstrate a unique capability to control the formation and properties of skin layer structures in relaxor ferroelectrics by adjusting defect concentration. It is shown that the skin layer is polar and both electrically and optically active.

Nature ◽  
2002 ◽  
Vol 416 (6876) ◽  
pp. 64-67 ◽  
Author(s):  
Toshihiro Ishikawa ◽  
Hiroyuki Yamaoka ◽  
Yoshikatsu Harada ◽  
Teruaki Fujii ◽  
Toshio Nagasawa

Author(s):  
Yu. M. Zubarev ◽  
M. A. Afanasenkov

The article considers the possibility of improving the performance of mineral-ceramic cutting plates by removing most of the defects on their working surface due to the formation of functional surface layers by ion-vacuum treatment. A model of a surface-hardened layer for VOK-60 type ceramics is proposed. Based on the configuration model of the substance, chemical elements are selected for modifying the surface layer of ceramics. The results of laboratory and production tests that showed an increase in the performance of ceramic plates after implantation by at least two times are presented.


2014 ◽  
Vol 89 ◽  
pp. 129-138 ◽  
Author(s):  
Toshihiro Ishikawa

Up to now, many types of inorganic fibers have been developed. The main purpose is to develop composite materials with lightweight and high fracture toughness. Of these, carbon fiber has already established a very big market. By the way, representative oxide fibers (alumina/silica-based fibers) show heat-resistance’s limitation at around 1200°C. In order to improve the heat-resistance, some types of eutectic oxide-fibers have been studied. On the other hand, SiC fibers with both heat-resistance and oxidation-resistance were developed over 30 years ago. After that, lots of improvements have been performed, and finally several types of excellent heat-resistant SiC-polycrystalline fibers, which can be used up to about 1800°C, were developed from polycarbosilane. Using these fibers, lots of applications have been considered in the fields of aerospace, nuclear system, and so on. Furthermore, making the best use of the aforementioned production process, several types of functional ceramic fibers with gradient-like functional surface layers also have been developed. In this paper, of these inorganic fibers, heat-resistant SiC fibers will be addressed along with historical view point on ceramic fibers.


2010 ◽  
Vol 654-656 ◽  
pp. 366-369 ◽  
Author(s):  
Tadeusz Frączek ◽  
Michał Olejnik ◽  
Jarosław Jasiński

The AISI 316L grade austenitic steel after glow discharge nitriding at a temperature of T = 598 K and for duration of  = 10,8 ks, for different variants of specimen arrangement in the glow-discharge chamber was investigated. In the first variant specimens were placed on the cathode and in the second variant specimens were positioned also on the cathode, but shielded with a booster screen. In order to assess the effectiveness of nitriding process variants a profile analysis examination of obtained surface layers, surface hardness tests and surface layer hardness profile examination, analysis of surface layer structures and corrosion resistance tests were carried out. It was found that application of a booster screen effects in a nitrogen diffusion depth increment into the 316L austenitic steel, resulting in a surface layer thickness escalation.


2014 ◽  
Vol 17 (5) ◽  
pp. 632-639 ◽  
Author(s):  
Anke Dalke ◽  
Anne Jung ◽  
Heinz-Joachim Spies ◽  
Rolf Zenker ◽  
Joachim Lerche

Author(s):  
Y.N. Zhukov ◽  
I.N. Tikhonov ◽  
A.I. Ogorodnikov

Parts made of modern brittle materials with high quality finish are widely used in manufacturing of optical and electronic devices as well as crucial assemblies in mechanical engineering products. Diamond machining enables generation of geometry without affecting the functional surface layers by heat. At the same time, brittle material cutting is accompanied by the formation of a defective layer on the machined surface due to the structural disturbances in the material caused by the applied cutting force. The paper discusses causes and the mechanism of the defective layer formation on the machined surface during non-free cutting of brittle materials and examines ways of reducing the size of the defective layer. Theoretical and computer-aided analysis is performed to determine the impact of the local stresses field in the zone of concentrated pressing force acting on the brittle plate surface. Using experimental methods, a defective layer formed after cutting notches on a silicon plate by a diamond tool is studied.


Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 434
Author(s):  
Zoia Duriagina ◽  
Volodymyr Kulyk ◽  
Taras Kovbasiuk ◽  
Bogdan Vasyliv ◽  
Andrii Kostryzhev

Laser alloying is an effective method to form functional surface layers (coatings) on metallic materials, particularly on stainless steels. Unique phase balance, dislocation substructure, and a possibility to obtain gradient microstructures after laser alloying slow down the surface degradation and increase the wear resistance. In this work, the optimal parameters of laser alloying and their effects on microstructure and properties were investigated for two stainless steels: ferritic AISI 420 and austenitic AISI 304. Three types of alloying plasters were used: 85Nb + 15 graphite, 85Nb + 15 liquid glass, and 15Fe + 30Ni + 20B + 10Si + 25 liquid glass (wt.%). The laser power density of 0.3 × 105 W/cm2 and beam scanning speed of 1990 mm/min were found to generate 220–320 μm thick coatings with complex microstructures. Phase balance in the coatings was studied with X-ray diffraction and magnetometric phase analyses. High microhardness (up to 16 GPa) and wear resistance were associated with the formation of martensite with some retained austenite and Nb-, Cr-, Si-, and B-rich particles in the surface layer of AISI 420 steel, and high dislocation density austenite strengthened with Ti-, Nb-, Cr-, and Si-rich particles in AISI 304 steel.


1982 ◽  
Vol 15 ◽  
Author(s):  
K. Ishiguro ◽  
N. Kawanishi ◽  
N. Sasaki ◽  
H. Nagaki ◽  
M. Yamamoto

ABSTRACTThe growth of surface layers on simulated waste glass during two different types of leaching has been studied in conjunction with their corrosion kinetics. Static and Soxhlet leach tests were performed in distilled water at a temperature of 100°C. Auger and ESCA analyses of solid samples after leaching showed that the layers consisted of two or three sublayers which were distinguished by their different components. The transition elements Fe and Ni, the rare-earths Nd and La, and Zn were concentrated in the layers, while Si, B and alkali were depleted in most of the layers. Growth kinetics of the layers followed approximately linear relations for the two types of leaching. Growth rates and elemental profiles of the layers depended upon the leaching conditions. Comparison between the leaching rate and the thickness of the layer showed that layers did not work as effective diffusion barriers until a threshold thickness was reached, which depended on the layer structures.


Author(s):  
Evgeny A. Pamfilov ◽  
◽  
Vladimir V. Kapustin ◽  
Galina A. Pilyushina ◽  
Elena V. Sheveleva ◽  
...  

Ensuring the competitiveness of enterprises of the forest complex is largely due to the level of reliable and high-performance equipment use, since this achieves a significant increase in the efficiency of timber harvesting and processing. At the same time, the required level of reliability of logging machines is largely determined by the performance of their functional units that carry out the basic technological operations. Accordingly, the development and implementation of ways and methods to improve the performance of functional units of machines is important when creating promising models of the specified equipment. This requires an analysis of the prospects and technical possibilities for improving the main mechanisms and units of logging machines and the factors limiting their performance. In order to improve the performance of machine functional units, it is essential to ensure the coordinated provision of favorable levels of a significant number of design and technological parameters. In particular, it is advisable to optimize the nature of the relative movement of the friction-contacting surfaces of the parts and reduce the loads acting on them. This is due to the fact that these factors determine the wear resistance and friction resistance, as well as the thermal mode of the machine operation, the stress state of the functional surface layers and the strength of the fixed joints. At the same time, the influence of operating conditions, the wear intensity and service life of the objects under study should be taken into account. This approach is due to the fact that tribotechnical units of logging machines perform their functions under the action of high shock, cyclic and vibration loads, in a wide range of harsh natural and climatic conditions characterized by low temperatures, high humidity, and the action of chemical and abrasive media. All this should be considered when justifying effective ways to improve the performance of functional units, including manipulators of logging machines, and achieved through regulated directional control of the properties of surface layers in the design and manufacture of friction-contacting parts. The paper substantiates the need to create scientific and engineering foundations for improving the performance of functional units and working bodies of machines, as well as achieving the required performance, durability and reliability. For this purpose, the tasks of further research aimed at obtaining information, the absence of which makes it impossible to create domestic import-substituting equipment, are clarified. For citation: Pamfilov E.A., Kapustin V.V., Pilyushina G.A., Sheveleva E.V. Improving the Performance of Working Bodies and Tribosystems of Harvester Technological Equipment. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 6, pp. 135–149. DOI: 10.37482/0536-1036-2021-6-135-149


1984 ◽  
Vol 75 ◽  
pp. 407-422
Author(s):  
William K. Hartmann

ABSTRACTThe nature of collisions within ring systems is reviewed with emphasis on Saturn's rings. The particles may have coherent icy cores and less coherent granular or frosty surface layers, consistent with thermal eclipse observations. Present-day collisions of such ring particles do not cause catastrophic fragmentation of the particles, although some minor surface erosion and reaccretion is possible. Evolution by collisional fragmentation is thus not as important as in the asteroid belt.


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