Pyrite micromorphology in three Australian Holocene sediments

Soil Research ◽  
1999 ◽  
Vol 37 (4) ◽  
pp. 637 ◽  
Author(s):  
Richard T. Bush ◽  
Leigh A. Sullivan
Keyword(s):  
Electron Microscopy ◽  
Sulfide Oxidation ◽  
Estuarine Sediments ◽  
X Ray Diffraction ◽  
Thin Coatings ◽  
X Ray ◽  
Holocene Sediments ◽  
Analytical Scanning Electron Microscopy ◽  
Scanning Electron

The distribution and morphology of pyrite in 3 Holocene estuarine sediments were examined using light microscopy, analytical scanning electron microscopy, and X-ray diffraction. The distribution and morphologies of pyrite were similar with pyrite being dispersed throughout the soil matrices as well as concentrated in root remnants and other macropores. The pyrite occurred in both framboidal and irregularly shaped dense clusters from 4 to 15 µm diameter, and also in loose clusters. Individual crystals in these clusters ranged in size from 1 to 2 µm. Pyrite crystals exhibited octahedral, pyritohedral, and equant anhedral (i.e. rounded globular) habit. Organic matter coatings and clay coatings were common around pyrite at each site. Thin coatings of monosulfide with an acicular morphology occurred around some framboidal clusters at one site. The distribution of framboids and individual crystals in the clayey matrix, root remnants, and other macropores indicates that the pyrite in these sediments has formed in situ. These data have important implications for the rate of sulfide oxidation and acid production from these soils.

Morphology of Polyethylene/Montmorillonite Nanocomposites Prepared by In Situ Polymerization

2013 ◽  
Vol 457-458 ◽  
pp. 244-247
Author(s):  
Min Li ◽  
Li Guang Xiao ◽  
Hong Kai Zhao
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
In Situ Polymerization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Reflection Peak ◽  
Basal Reflection ◽  
Scanning Electron

Polyethylene/montmorillonite (PE/MMT) nanocomposites were prepared by in situ polymerization. The morphology of MMT/MgCl2/TiCl4 catalyst and PE/MMT nanocomposites was investigated by scanning electron microscopy (SEM). It can be seen that MMT/MgCl2/TiCl4 catalyst remained the original MMT sheet structures and many holes were found in MMT and the morphology of PE/MMT nanocomposites is part of the sheet in the form of existence, as most of the petal structure. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were carried out to characterize all the samples. XRD results reveal that the original basal reflection peak of PEI1 and PEI2 disappears completely and that of PEI3 become very weak. MMT/MgCl2/TiCl4 catalyst was finely dispersed in the PE matrix. Instead of being individually dispersed, most layers were found in thin stacks comprising several swollen layers.

Fabrication of TiAl/Ti2AlC Composite by Reaction Hot Pressing

2011 ◽  
Vol 52-54 ◽  
pp. 842-845 ◽  
Author(s):  
Jian Feng Zhu ◽  
Wen Wen Yang ◽  
Yi Ping Gong
Keyword(s):  
Electron Microscopy ◽  
Reaction Process ◽  
Hot Press ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Composite ◽  
The Matrix ◽  
Morphology Characteristics ◽  
Scanning Electron

TiAl/Ti2AlC in situ composite was successfully fabricated by hot-press-assisted reaction process from the mixture of Ti, Al and carbon black. The phase formation and transformation were investigated in detail by X-ray diffraction (XRD) and the morphology characteristics were also studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that when the mixed powders were hot pressed at 1300 °C for 1 h, full dense and highly pure TiAl/Ti2AlC composite was synthesized. The TiAl was the matrix phase and the in situ synthesized Ti2AlC was reinforcing phase. The reaction process was also discussed.

Microstructure of In Situ Reaction TiB2/Zn-30Al-1Cu Composites Prepared by Spray Deposition Process

2015 ◽  
Vol 1120-1121 ◽  
pp. 572-575
Author(s):  
Hong Wei Liu ◽  
Feng Wang ◽  
Qiang Zhang ◽  
Xi Wu Li ◽  
Zhi Hui Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Spray Deposition ◽  
Deposition Process ◽  
Deposition Technique ◽  
X Ray Diffraction ◽  
X Ray ◽  
Α Phase ◽  
Scanning Electron

An innovative spray deposition technique has been applied to produce in situ TiB2/Zn-30Al-1Cu composites. The microstructures of the spray-deposited composite were studied using optical microscopy, scanning electron microscopy, and X-ray diffraction. Both theoretical and experimental results have shown that the TiB2particulates are formed in the microstructure. It was found that the TiB2particles were distributed in Zn-30Al-1Cu matrix uniformly, and the TiB2particles are about 2 μm in size. Moreover, the presence of the TiB2particles was led to increasing of α’ phase with less 2 μm size in the composites which have a tendency to decompose to α+η structure.

Electro-Less Ni-P Plating Coating of In Situ TiCp/Al-4.5wt.%Cu Vomposites

2015 ◽  
Vol 817 ◽  
pp. 593-598
Author(s):  
Yan Feng Liang ◽  
Sheng Quan Dong ◽  
Gao Hong Li
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Citric Acid ◽  
Optical Microscopy ◽  
X Ray Diffraction ◽  
Citric Acid Concentration ◽  
X Ray ◽  
In Situ Tic ◽  
Scanning Electron

In situ TiCp/Al-4.5wt.%Cu composites have been coated using an electro-less Ni-P plating technique. The morphology and composition of the plating coating have been examined by scanning electron microscopy, optical microscopy, and X-ray diffraction. The results indicated that the coating had a high-phosphorus amorphous microstructure. The coatings microstructures showed significantly changes when the citric acid concentration in the chemical bath was varied in the range 16-20g/L.

Spray dried hydroxyapatite-polyvinyl alcohol biocomposites

2016 ◽  
Vol 36 (8) ◽  
pp. 795-804 ◽  
Author(s):  
Tuğba Başargan ◽  
Nalan Erdöl-Aydın ◽  
Gülhayat Nasün-Saygılı
Keyword(s):  
Electron Microscopy ◽  
Polyvinyl Alcohol ◽  
Spray Dryer ◽  
Drying Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pva Solutions ◽  
Spray Dried ◽  
Scanning Electron

Abstract In this study, hydroxyapatite/polyvinyl alcohol (HAp-PVA) biocomposites were prepared using a spray drying method. HAp-PVA solutions fed to spray dryer were prepared by two different routes, namely, physical and in situ biomimetric methods. In the former method, HAp was synthesized without the presence of polymer and then HAp particles were incorporated into a PVA solution. In the second one, hydroxyapatite was in situ synthesized in the presence of PVA. Experiments were also run to investigate the effect of the molecular weight of PVA on the structure of spray-dried biocomposites. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and particle size analyses were performed to characterize the produced HAp-PVA composites.

Microstructure Evolution of In Situ Synthesized VC Reinforced Iron Matrix Composites

2012 ◽  
Vol 217-219 ◽  
pp. 71-74
Author(s):  
Jing Wang ◽  
Si Jing Fu ◽  
Shu Yong Jiang ◽  
Hong Cheng
Keyword(s):  
Electron Microscopy ◽  
In Situ Synthesis ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
Iron Matrix ◽  
X Ray ◽  
Matrix Microstructure ◽  
The Matrix ◽  
Scanning Electron

Iron matrix composite reinforced with VC reinforcements was produced by in situ synthesis technique. The microstructure of the composites was characterized by X-ray diffraction and scanning electron microscopy. The micrographs revealed the morphology and distribution of the reinforcements. The results show that the composite consists of VC carbide as the reinforcing phase and α-Fe as the matrix. The distribution of spherical VC particulates in iron matrix is uniform, and the matrix microstructure of Fe-VC composite is pearlite.

Oxidation of Micro-Sized Spherical Aluminium Particles

2011 ◽  
Vol 696 ◽  
pp. 290-295 ◽  
Author(s):  
Vladislav Kolarik ◽  
Maria del Mar Juez-Lorenzo ◽  
Harald Fietzek
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Oxidation Behaviour ◽  
X Ray Diffraction ◽  
Oxide Formation ◽  
X Ray ◽  
Isothermal Conditions ◽  
Heating Up ◽  
Scanning Electron

Micro-sized spherical Al particles have recently attracted interest for the development of a new concept for coatings based on their capability to form hollow alumina spheres and aluminized diffusion zones in the substrate. For understanding better their oxidation behaviour, spherical µm-Al particles with different sizes were oxidized in air on heating up to 1300°C and under isothermal conditions at 800°C and 850°C. The oxide formation was studiedin situby high temperature X-ray diffraction and the oxidised particles were analysed by scanning electron microscopy. On heating the µm-Al particles begin to form a g-Al2O3scale before reaching the melting point and the molten Al is kept within the g-Al2O3shell. On further heating q-Al2O3is detected, which forms simultaneously with the g-Al2O3. The g-Al2O3/ q-Al2O3scale is stable and protective under isothermal conditions up to 800°C within the investigated times. On further heating the g-Al2O3and q-Al2O3transform simultaneously to a-Al2O3in a temperature range of 850°C to 1100°C. Under isothermal conditions the g à a-Al2O3transformation is observed after 160 min at 850°C. During the g à a-Al2O3transformation shrinkage occurs that leads to formation of pores. A model is proposed describing the mechanism that leads to the formation of the observed whiskers morphologies during the g à a-Al2O3transformation.

Fabrication of Conductive Alumina by Gelcasting and Reduction Sintering

2006 ◽  
Vol 317-318 ◽  
pp. 657-660 ◽  
Author(s):  
Minoru Takahashi ◽  
Koichiro Adachi ◽  
Ruben L. Menchavez ◽  
Masayoshi Fuji
Keyword(s):  
Electron Microscopy ◽  
Electrical Resistance ◽  
Nitrogen Atmosphere ◽  
X Ray Diffraction ◽  
Electrically Conductive ◽  
X Ray ◽  
New Process ◽  
Plastic Mould ◽  
Scanning Electron

In this study, we propose a new process to fabricate electrically conductive alumina by gelcasting and reduction sintering. The process used the conventional gelcasting method except for varying amounts of monomer at 2.8, 5.5, and 8.0 wt.% relative to the weight of the slurry. In the plastic mould, the slurry was under in situ solidification for 3 hrs at 25oC to achieve gelation. The freshly gelled bodies were demolded, carefully dried, and then sintered at 1100oC, 1300oC, and 1550oC in nitrogen atmosphere. The holding times at 1100oC and 1300oC was 2 hours, while at 1550oC were 2, 4, and 6 hrs. The sintered alumina body was characterized by electrical property, X-ray diffraction, and scanning electron microscopy. Results showed that monomer additions and sintering schedule significantly affect in lowering electrical resistance. The low value was 3.6×106 +cm at 8.0wt.% monomer addition and sintering at 1550oC for 2 hrs. The effect of physical properties on electrical conductivity and the corresponding reaction mechanism were discussed in details.

scholarly journals Microstructures of Three In-Situ Reinforcements and the Effect on the Tensile Strengths of an Al-Si-Cu-Mg-Ni Alloy

2018 ◽  
Vol 8 (9) ◽  
pp. 1523 ◽  
Author(s):  
Lusha Tian ◽  
Yongchun Guo ◽  
Jianping Li ◽  
Feng Xia ◽  
Minxian Liang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Simultaneous Formation ◽  
X Ray ◽  
Transmission Electron ◽  
Ni Alloy ◽  
Al3ti Phase ◽  
Scanning Electron

In the present paper, the microstructures of three kinds of in-situ reinforcements Al-Ti-C, Al-Ti-B, and Al-Ti-B-C-Ce were deeply investigated using a combination of scanning electron microscopy, X-ray diffraction spectroscopy, and transmission electron microscopy. The effect of in-situ reinforcements on the room temperature and elevated temperature (350 °C) tensile strengths of Al-13Si-4Cu-1Mg-2Ni alloy were analyzed. It is found that doping with trace amounts of B and Ce, the size of the Al3Ti phase in the in-situ reinforced alloy changed from 80 µm (un-reinforced) to about 10 µm, with the simultaneous formation of the AlTiCe phase. The Al-Ti-B-C-Ce reinforcement which is rapid solidified, was more effective and superior to enhance the tensile strengths of the Al-13Si-4Cu-1Mg-2Ni alloy, both at room and high temperatures than those of addition other reinforcements. The room temperature (RT) strength increased by 19.0%, and the 350 °C-strength increased by 18.4%.

The occurrence of palygorskite in Quaternary sediments of the coastal plain of north-west Egypt

Clay Minerals ◽  
1980 ◽  
Vol 15 (1) ◽  
pp. 77-83 ◽  
Author(s):  
H. Hassouba ◽  
H. F. Shaw
Keyword(s):  
Electron Microscopy ◽  
Coastal Plain ◽  
Beach Ridge ◽  
X Ray Diffraction ◽  
Quaternary Sediments ◽  
Beach Ridges ◽  
X Ray ◽  
North West ◽  
Scanning Electron

AbstractSediments from a Quaternary beach ridge complex along the coastal plain of north-west Egypt have been examined by X-ray diffraction and optical and scanning electron microscopy. Palygorskite was identified in the caliche capping the beach ridges and in the gypsiferous marls between the ridges; petrographic evidence indicated that this had formed authigenically in both environments. Examples are thus provided of the pedogenic and evaporative in situ formation of palygorskite.

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