Microstructure of Recycled Gypsum Plaster by SEM

Building Construction ◽

Construction Waste ◽

Gypsum Plaster ◽

Recycled Gypsum

Gypsum waste from building constructions is a material which can contaminate the soil and groundwater if is disposed directly in the soil or landfill without any control. In Brazil, these wastes are considered a recycle and/or recovery material, but the research of gypsum plaster recycling are very few at this moment. In this way, this work presents the microstructural characterization of two types of recycled plaster. The recycled plaster was produced by a grinding and calcination the building construction waste. Microstructural characteristics were evaluated by SEM observations. The results show similarities between crystals of recycled and commercial plasters.

Structural Transformations of Boron Nitride Powders Obtained by Mechanical Milling Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.68.101 ◽

2009 ◽

Vol 68 ◽

pp. 101-108

Author(s):

Rodrigo A. Esparza ◽

J. Ayala ◽

C. Ángeles-Chávez ◽

G. Rosas ◽

Ramiro Pérez

Keyword(s):

Boron Nitride ◽

Structural Transformations ◽

Milling Process ◽

X Ray Diffraction ◽

X Ray ◽

Diffraction Patterns ◽

Milled Powders

Mechanical milled powders of boron nitride were obtained. The microstructural characterization of these milled powders was carried out using X-ray diffraction technique. Insights on the nature of the crystalline phases obtained in these milled powders were obtained between comparisons of theoretical and experimental X-ray diffraction patterns. Observations on the phase transformations have been carried out using calorimetry and thermogravity experiments. Morphological and microstructural characteristics of nanocrystals are obtained using SEM and HRTEM instruments.

Microstructural Characterization of Ni(Co)CrAlY Powders Designed for Thermal Spraying of Bondcoat for TBC Systems

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.203-204.435 ◽

2013 ◽

Vol 203-204 ◽

pp. 435-438 ◽

Cited By ~ 1

Author(s):

Grzegorz Moskal

Keyword(s):

Phase Composition ◽

Chemical Composition ◽

Thermal Spraying ◽

Atmospheric Plasma Spraying ◽

Atmospheric Plasma ◽

Study Results ◽

Tbc Systems

The paper presents the study results concerning microstructural characteristics of the Ni(Co)CrAlY type powders designed for the bondcoat spraying with the plasma method for TBC layers obtained by the atmospheric plasma spraying (APS). Three types of powders with the following chemical composition Ni-23Co-17Cr-12.5Al-0.45Y, Co-32Ni-21Cr-8Al-0.5Y and Ni-22Cr-10Al-Y were subjected to analysis. The assessment of surface morphology and inner structure of powders (SEM) was made. Chemical composition (EDX, OES-ICP) of the powders was determined. Phase composition by using XRD and EBSD methods was also analysed.

Microstructural Characteristics of Ti-Co Alloys for Biomedical Applications

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.791-793.469 ◽

2013 ◽

Vol 791-793 ◽

pp. 469-473 ◽

Cited By ~ 1

Author(s):

Xing Zhi Pang ◽

Jing Hu ◽

Yong Zhong Zhan

Keyword(s):

Biomedical Applications ◽

Eutectic Reaction ◽

Eutectoid Reaction ◽

Cast State ◽

Tissue Replacement ◽

Potential Applications ◽

Co Alloys

TiCo alloys are important biomedical materials for both scientific and technological interests due to their potential applications as hard tissue replacement (HTR). The microstructural characteristics of the alloys in this system are of both scientific and technological interests. This work presents the results of microstructural characterization of as-cast TiCo alloys using a combination of various experimental methods. The results confirm that there are two variants of the Laves phase TiCo2, i.e. h-TiCo2 and c-TiCo2 exist in this system of as cast state. The eutectic reaction L(β-Ti)+ Ti2Co is determined to be occur at at 23 at.% Co, 1020 °C. Four peritectic reactions, i.e. L+ TiCo Ti2Co, L+ TiCo (c-TiCo2), L+(c-TiCo2) (h-TiCo2) and L+Co TiCo3 occur at 1058 °C, 1235 °C, 1210 °C, and 1190 °C, respectively. Eutectoid reaction (βTi) (αTi)+ Ti2Co occurs at 9 at.% Co, 685 °C.

Characterization of Portuguese Historical Gypsum Mortars: A Comparison between Two Case Studies

Materials Science Forum ◽

10.4028/www.scientific.net/msf.636-637.1258 ◽

2010 ◽

Vol 636-637 ◽

pp. 1258-1265 ◽

Cited By ~ 8

Author(s):

T. Freire ◽

António Santos Silva ◽

R. Veiga ◽

J. de Brito

Keyword(s):

Elasticity Modulus ◽

Physical And Mechanical Properties ◽

Historical Period ◽

Capillary Absorption ◽

Geographical Regions ◽

Gypsum Plaster ◽

Xix Century ◽

Absorption Dynamic

The use of gypsum plaster for interior covering of walls and ceilings in the Portuguese architecture was particularly expressive in the period between the XVIII and the XX century. However, information about this important heritage is almost inexistent, which is leading to a fast loss of important patrimony. In this paper, the results of the characterization of gypsum plaster samples belonging to two buildings from the same historical period (end of the XIX century and beginning of the XX), situated in distant geographical regions of Portugal are presented and discussed. XRD, TGA-DTA, optical microscopy and SEM-EDS observations were used for the chemical and microstructural characterization. Some physical and mechanical properties, such as capillary absorption, dynamic elasticity modulus and compressive strength were also determined and a relationship between the characteristics observed in the samples and the technology associated to their use and application on site, as well as the possible existence of regional influences on all these aspects, are discussed.

Hydraulic activity and microstructural characterization of new fly ash–belite cements synthesized at different temperatures

Journal of Materials Research ◽

10.1557/jmr.1999.0359 ◽

1999 ◽

Vol 14 (6) ◽

pp. 2680-2687 ◽

Cited By ~ 34

Author(s):

A. Guerrero ◽

S. Goñi ◽

A. Macías ◽

M. P. Luxán

Keyword(s):

Fly Ash ◽

Synthesis Temperature ◽

Water Mixture ◽

X Ray Diffraction ◽

Hydraulic Activity ◽

Different Temperatures ◽

Belite Cement

The influence of the synthesis temperature of a new fly ash–belite cement (FABC) on its hydraulic activity and microstructural characteristics is discussed in this work. Three types of FABC were synthesized at 700, 800, and 900 °C after a previous hydrothermal treatment at 200 °C of the fly ash, CaO, and water mixture. The hydraulic activity of the pastes was evaluated during a period of 200 days from mixing through the combined water content, previously determined from thermogravimetric analyses, and the hydration advance degree by x-ray diffraction (XRD). The microstructure characterization of the pastes was studied by scanning electron microscopy (SEM).

Microstructural characterization of CoPtCr/Cr thin film disks by cross-section TEM and elongated probe micro-diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088129 ◽

1991 ◽

Vol 49 ◽

pp. 762-763

Author(s):

M.A. Parker ◽

K.E. Johnson ◽

C. Hwang ◽

A. Bermea

Keyword(s):

Magnetic Recording ◽

Electron Probe ◽

Crystallographic Structure ◽

Recording Media ◽

Layer By Layer ◽

Cross Sectional ◽

New Techniques ◽

Polished Side

We have reported the dependence of the magnetic and recording properties of CoPtCr recording media on the thickness of the Cr underlayer. It was inferred from XRD data that grain-to-grain epitaxy of the Cr with the CoPtCr was responsible for the interaction observed between these layers. However, no cross-sectional TEM (XTEM) work was performed to confirm this inference. In this paper, we report the application of new techniques for preparing XTEM specimens from actual magnetic recording disks, and for layer-by-layer micro-diffraction with an electron probe elongated parallel to the surface of the deposited structure which elucidate the effect of the crystallographic structure of the Cr on that of the CoPtCr.XTEM specimens were prepared from magnetic recording disks by modifying a technique used to prepare semiconductor specimens. After 3mm disks were prepared per the standard XTEM procedure, these disks were then lapped using a tripod polishing device. A grid with a single 1mmx2mm hole was then glued with M-bond 610 to the polished side of the disk.

Microstructural Characterization of Au-Ge-Ni based ohmic contacts to GaAs/AlGaAs modfet device

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126433 ◽

1987 ◽

Vol 45 ◽

pp. 326-327

Author(s):

A.K. Rai ◽

A.K. Petford-Long ◽

A. Ezis ◽

D.W. Langer

Keyword(s):

Contact Resistance ◽

Ohmic Contact ◽

Ohmic Contacts ◽

Almost Everywhere ◽

Spacer Layer ◽

Good Contact ◽

The Relationship ◽

Lower Contact

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.

Microstructural characterization of a cast RENi5-based alloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151714 ◽

1993 ◽

Vol 51 ◽

pp. 1176-1177

Author(s):

G. M. Micha ◽

L. Zhang

Keyword(s):

Electron Microscopy ◽

Rare Earth ◽

Binary Compound ◽

Nickel Metal ◽

Cast Material ◽

Nickel Metal Hydride ◽

Transmission Electron ◽

Cast Condition

RENi5 (RE: rare earth) based alloys have been extensively evaluated for use as an electrode material for nickel-metal hydride batteries. A variety of alloys have been developed from the prototype intermetallic compound LaNi5. The use of mischmetal as a source of rare earth combined with transition metal and Al substitutions for Ni has caused the evolution of the alloy from a binary compound to one containing eight or more elements. This study evaluated the microstructural features of a complex commercial RENi5 based alloy using scanning and transmission electron microscopy.The alloy was evaluated in the as-cast condition. Its chemistry in at. pct. determined by bulk techniques was 12.1 La, 3.2 Ce, 1.5 Pr, 4.9 Nd, 50.2 Ni, 10.4 Co, 5.3 Mn and 2.0 Al. The as-cast material was of low strength, very brittle and contained a multitude of internal cracks. TEM foils could only be prepared by first embedding pieces of the alloy in epoxy.