XPS-Study of Excimer Laser-Reconstructed Alumina Surface

1996 ◽  
Vol 441 ◽  
Author(s):  
D. G. Georgiev ◽  
K. Kolev ◽  
L. D. Laude ◽  
O. Brouxhon
Keyword(s):  
Surface Modifications ◽  
Optical Methods ◽  
Excimer Lasers ◽  
Ceramic Surface ◽  
Alumina Surface ◽  
Ceramic Processing ◽  
Alumina Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Xps Study

AbstractSintered alumina ceramics are recognized as important industrial materials. For many of their applications however, a suitable pretreatment is required aiming at improving the ceramic surface properties. Since excimer lasers have recently proved to be efficient in ceramic processing, a detailed investigation of sintered alumina surface modifications upon excimer irradiation has been performed. In a previous work the results of low-angle X-ray diffraction analysis reveal emergence of the alumina gamma-phase within the upper 10nm of the material. This presence is further demonstrated by the XPS-study reported here. The photoelectron data are compared with information obtained by optical methods.

Experimental Investigation of Surface Modified Abaca Fibre

2020 ◽  
Vol 978 ◽  
pp. 291-295 ◽  
Author(s):  
Agnivesh Kumar Sinha ◽  
Harendra Kumar Narang ◽  
Somnath Bhattacharya
Keyword(s):  
Polymer Composites ◽  
Amorphous Materials ◽  
Crystallinity Index ◽  
Surface Modifications ◽  
Xrd Analysis ◽  
Natural Fibres ◽  
Ftir Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Modified

Natural fibres have gained popularity due to their use in fabrication of biodegradable polymer composites which are not only non-polluting but are also light weight and inexpensive. Abaca fibres are known for their remarkable properties for which their polymer composites are used in automotive applications. However, hydrophilicity and compatibility with polymer matrices are the two major drawbacks of natural fibres which restrict their use as reinforcements in polymer composites. Therefore, present study deals with the surface modifications of abaca fibre using potassium permanganate and sodium hydroxide solutions to enhance crystallinity and reduce hydrophilicity of abaca fibres. Further, the surfaces of untreated and treated fibre were investigated with the help of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. Surface treatment of abaca fibre led to the removal of unwanted wax, and other amorphous materials which was confirmed through FTIR analysis. Crystallinity index was found to be 57%, 59% and 61% for untreated, NaOH treated and KMnO4 treated abaca fibre respectively.

Interface Reactions of Joining Al2O3 Ceramics by Microwave Method

2013 ◽  
Vol 753-755 ◽  
pp. 388-391
Author(s):  
Ying Na Zhao ◽  
Xiong Feng Zeng ◽  
Gui Qin Hou ◽  
Wen Li Zhang
Keyword(s):  
Interfacial Microstructure ◽  
Parent Material ◽  
Joint Interface ◽  
Ceramic Surface ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Interface Reactions ◽  
Interface Phase ◽  
Element Migration

Nanometer Si powders were used as interlayer materials, which were expected to be microwave heated rapidly and reacted with the surface of Al2O3ceramics to form the low eutectoid compound. The phenomena of element migration of joint samples were investigated by energy dispersive spectroscopy (EDS) and the interface phase transition was analyzed by X-ray diffraction (XRD). The results indicated that the low eutectoid compound of the joint interface wetted and penetrated to the ceramic surface. The variation of micro-hardness at the interface across the parent material was measured by micro-hardness instrument and the interfacial microstructure and the fracture surface were investigated by scanning electron microscopy (SEM).

scholarly journals The relationship between microstructure and mechanical properties of directly bonded copper-alumina ceramics joints

2014 ◽  
Vol 62 (1) ◽  
pp. 23-32 ◽  
Author(s):  
K. Pietrzak ◽  
W. Olesinska ◽  
D. Kalinski ◽  
A. Strojny-Nedza
Keyword(s):  
Mechanical Strength ◽  
Transition Layer ◽  
Diffraction Method ◽  
Alumina Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Three Point Bending ◽  
Microscopy Method ◽  
Materials Used ◽  
The Individual

Abstract The effect of phase transformations induced in the surface layer of alumina ceramics during its direct joining with copper activated with oxygen or titanium on the mechanical strength of the ceramic/copper joints was examined. The materials used in the experiments were an alumina single crystal, alumina ceramics (97.5 wt% Al2O3), the cermet mixtures: Cu-Cu2O with 10-50 wt% of Cu2O, copper with 5 wt% of Ti, and copper with 5 wt% of Ti and 10 wt% of Ag. The microstructure of the transition layer was examined by the X-ray diffraction method (XRD), scanning electron microscopy method (SEM) and energy dispersive x-ray spectroscopy (EDX). The mechanical strength of the joints was measured using the three-point bending method. The amount of oxygen optimal for the joining process was determined. It has been demonstrated that the cohesion of the joints depends not only on the formation of the individual phases but also, or even primarily, on the microstructure of the transition layer formed between them.

Fabrication and Characterization of a Feldspar-Alumina for Dental Ceramic

2010 ◽  
Vol 160-162 ◽  
pp. 424-427
Author(s):  
Guang Lei Zhang ◽  
Guo Qiang Qin ◽  
Yuan Hua Zhang ◽  
Pu Cheng ◽  
Chang Tao Shao
Keyword(s):  
Sinter Temperature ◽  
Bending Strength ◽  
Dental Ceramics ◽  
Alumina Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fabrication And Characterization ◽  
Sintering Method ◽  
Scanning Electron

Feldspar-alumina dental ceramics were produced by impressed sintering method and characterized by X-ray diffraction and scanning electron microscope techniques. The machinability of the obtained alumina ceramics was evaluated by grinding capacity in the simulative grinding experiment. The results show that an appropriate amount of feldspar additive can reduce the sinter temperature and improve density, bending strength and machinability of alumina dental ceramics. Under 10 wt% feldspar and 1450 °C sinter temperature, the relative density and bending strength of ceramic reached 93.62% and 235MPa, respectively.

High Temperature Chemical Interaction Between SSiC Substrates and Ag-Cu Based Liquid Alloys in Vacuo

2006 ◽  
Vol 509 ◽  
pp. 111-116 ◽  
Author(s):  
Jorge López-Cuevas ◽  
Juan Carlos Rendón-Angeles ◽  
J.L. Rodríguez-Galicia ◽  
M. Herrera-Trejo ◽  
J. Méndez-Nonell
Keyword(s):  
Electron Microscopy ◽  
Chemical Interaction ◽  
Silica Film ◽  
Liquid Alloys ◽  
Ceramic Surface ◽  
X Ray Diffraction ◽  
Metal Interface ◽  
X Ray ◽  
Metal Ceramic ◽  
Scanning Electron

The interfaces formed at 850 °C under vacuum between polished or oxidized substrates of pressureless sintered α-SiC (SSiC) and Cusil, Cusil-ABA and Incusil-ABA brazing alloys have been characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. No chemical interaction is observed for Cusil on both SSiC substrates. In contrast, the Ti contained in the Cusil-ABA and Incusil-ABA alloys promotes the occurrence of chemical reactions at the metal/ceramic interface with both SSiC substrates. The formation of TiC and Ti5Si3 is observed for Cusil-ABA and Incusil-ABA on untreated SSiC, following the sequence SiC → TiC → Ti5Si3 at the metal/ceramic interface. The formation of Ti5Si3 and Cu3Ti3O, following the sequence SiC → Ti5Si3 → Cu3Ti3O, is observed for both Ti-containing alloys on pre-oxidized SSiC. During the wetting experiments, Ti5Si3 and Cu3Ti3O detach from the ceramic surface, floating away from the ceramic/metal interface into the liquid alloy, where the latter phase partially dissolves. It is concluded that for both Ti-containing alloys in contact with pre-oxidized SSiC, the Ti remaining after the reaction with the silica film is insufficient to decrease the contact angle to the values observed for untreated SSiC or to produce a strong metal/ceramic joint.

Synthesis of Alumina Powders by Mechanical Activation

2006 ◽  
Vol 530-531 ◽  
pp. 655-660
Author(s):  
Adriana Scoton Antonio Chinelatto ◽  
C. Lago ◽  
S.R.M. Antunes ◽  
A.C. Antunes ◽  
Osvaldo Mitsuyuki Cintho ◽  
...  
Keyword(s):  
Pechini Method ◽  
High Energy ◽  
Alumina Ceramics ◽  
X Ray Diffraction ◽  
Electrical And Optical Properties ◽  
X Ray ◽  
Aluminum Nitrate Nonahydrate ◽  
Ft Ir ◽  
Reactive Alumina ◽  
Nitrate Nonahydrate

Alumina is utilized in many areas of modern industry because of its unique mechanical, electrical and optical properties. Various methods are been employed for produce alumina for different end uses. The preparation of fine and sintering-reactive alumina powders is probably one of the most important steps for production alumina ceramics with controlled microstructure. In this work, it was studied the production of alumina powders by “Pechini” method associated to highenergy milling. For this, it was prepared the resin by Pechini method, using aluminum nitrate nonahydrate. This resin was calcined at 500oC. Then, the calcined powders were submitted a high energy milling for different times. The powders mechanically activated were characterized by x ray diffraction, FT-IR and scanning electronic microscopic. After milling, the powders were calcined at 900oC. The results showed that the alumina phase transitions and powders characteristics were modified when the step of activation mechanical was introduced.

Effect of La2O3 substitutions on structure and dielectric properties of Bi2O3–ZnO–Nb2O5-based pyrochlore ceramics

1999 ◽  
Vol 14 (2) ◽  
pp. 546-548 ◽  
Author(s):  
Hong Wang ◽  
Desheng Zhang ◽  
Xiaoli Wang ◽  
Xi Yao
Keyword(s):  
Crystal Structure ◽  
Dielectric Properties ◽  
Crystal Structures ◽  
Structure Change ◽  
Lower Amount ◽  
Ceramic Processing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conventional Ceramic Processing ◽  
Structure Properties

The effect of La2O3 substitutions on structure and dielectric properties of Bi2O3 –ZnO–Nb2O5-based ceramics was investigated. Bi1.5-xLaxZn0.5(Zn0.5Nb1.5)O7 samples were prepared by conventional ceramic processing technology. The crystal structure of the Bi1.5Zn0.5(Zn0.5Nb1.5)O7 sample was characterized as a pure cubic pyrochlore. With a lower amount of La2O3 substitution, the crystal structures were still cubic pyrochlore. Superlattice x-ray diffraction line was identified for some compositions. With the increasing amount of La2O3 substitution, the crystal structure gradually transformed from pure cubic pyrochlore to LaNbO4 phase. The dielectric properties regularly changed with the structure change. The structure-properties relations of the ceramics are discussed.

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