scholarly journals Effective Utilization of Limonitic Nickel Laterite via Pressurized Densification Process and Its Relevant Mechanism

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 750
Author(s):  
Yuxiao Xue ◽  
Deqing Zhu ◽  
Jian Pan ◽  
Zhengqi Guo ◽  
Congcong Yang ◽  
...  
Keyword(s):  
Industrial Application ◽  
External Pressure ◽  
Front Velocity ◽  
Thick Wall ◽  
Thin Wall ◽  
Sintering Process ◽  
Effective Utilization ◽  
New Process ◽  
Fuel Rate ◽  
Mineral Compositions

Limonitic laterite contains low iron and nickel grades and much high smelting minerals and loss on ignition (LOI), identified as refractory iron ore for sintering. Thus, sinter pot tests of limonitic laterite via pressurized densification sintering and its intensification mechanism were conducted, and the industrial application prospect was explored. The results indicate that the sintering performance of the limonitic laterite of the new process is significantly improved with the tumble index and productivity increased by 19.2% and 18.6%, respectively, and solid fuel rate lowered by 10.3%. The external pressure field promotes the synchronization of heat front velocity and combustion front velocity for better sintering heat and mass transfer conditions, which also greatly improves the mineral compositions and microstructure of the product sinter. The microstructure is converted from large thin-wall pores into small thin-wall or large thick-wall pores with the sinter porosity decreased by 42.4%. Much close interlocking texture between hercynite and silico-ferrite of calcium and alumina (SFCA) is formed with hercynite grains aggregation and growth, and SFCA amount substantially increased. The better sintering performance will bring about a remarkable economic benefit of 282.78 million RMB/a if the industrial application is implemented. The pressurized densification sintering process is considered as one of the effective technologies for improving limonitic laterite sintering.

MICROSTRUCTURE ANALYSIS OF MOSO BAMBOO (Phyllostachys pubescens MAZEL) SURFACE AFTER UV RADIATION

2019 ◽  
Vol 27 (01) ◽  
pp. 1950090
Author(s):  
HAIXIA YU ◽  
XIN PAN ◽  
WEIMING YANG ◽  
WENFU ZHANG ◽  
XIAOWEI ZHUANG
Keyword(s):  
Uv Radiation ◽  
Cell Walls ◽  
Uv Light ◽  
Parenchyma Cell ◽  
Moso Bamboo ◽  
Thick Wall ◽  
Phyllostachys Pubescens ◽  
Thin Wall ◽  
Intercellular Spaces ◽  
Parenchyma Cell Walls

Bamboo material is widely used in outdoor applications. However, they are easily degraded when exposed to sunlight, their smooth surface will gradually turn to rough, and small cracks will appear and finally develop to large cracks. The paper presents a first-time investigation on the microstructure changes in the tangential section of Moso bamboo (Phyllostachys pubescens Mazel) radiated by artificial UV light. The results showed that the cracks mainly appeared at intercellular spaces of fibers where lignin content was high, the parenchyma cell walls and neighbor pits where the cell wall was very thin and more vulnerable than the other parts. In addition, the part of raised area and pit cavity tended to absorb more UV light radiation and showed more and larger cracks than the otherwhere. Cracks at the intercellular spaces of fibers were larger and bigger than those on the parenchyma cell walls. The cracks on the pits of the parenchyma cell walls normally appeared at one pit and then extended to the several surrounding pits. Bordered pits cavity showed more and larger cracks than the pits on the thin wall cells. The simple pits on the thick wall cells and the fiber cells were unaffected by UV radiation.

Development of Semi-Solid Die Casting Product Design and Die Design Technology for Aluminium Alloy Clamp

2016 ◽  
Vol 256 ◽  
pp. 334-339 ◽  
Author(s):  
Song Chen ◽  
Fan Zhang ◽  
You Feng He ◽  
Da Quan Li ◽  
Qiang Zhu
Keyword(s):  
Product Design ◽  
Die Casting ◽  
Casting Process ◽  
Die Design ◽  
Thick Wall ◽  
Thin Wall ◽  
Gating System ◽  
Cross Sectional ◽  
Die Casting Process ◽  
Semi Solid

Semi-solid slurry has significantly higher viscosity than liquid metal. This character of fluidity makes product design and die design, such as gating system, overflow and venting system, be different between these two die casting processes. In the present paper, taking a clamp product as an example, analyses the product optimization and die design by comparing the experimental and computational numerical simulation results. For the clamp, product structure is designed to be suitable for characters of SSM die casting process. The gating system is designed to be uniform variation of thickness, making the cross-sectional area uniformly reduce from the biscuit to the gate. This design ensures semi-solid metal slurry to fill die cavity from thick wall to thin wall. Gate position is designed at the thickest location, the gate shape of semi-solid die casting is set to be much bigger than traditional liquid casting. A good filling behaviour can be achieved by aforementioned all these design principles and it will be helpful to the intensification of pressure feeding after filling.

scholarly journals Shape Memory NiTi and NiTiCu Alloys Obtained by Spark Plasma Sintering Process

2015 ◽  
Vol 13 ◽  
pp. 83-90 ◽  
Author(s):  
Cristiana Diana Cristea ◽  
Magdalena Lungu ◽  
Alexander M. Balagurov ◽  
Virgil Marinescu ◽  
Otilia Culicov ◽  
...  
Keyword(s):  
Shape Memory ◽  
Intermetallic Compounds ◽  
Spark Plasma Sintering ◽  
Sintering Process ◽  
Transformation Behavior ◽  
Plasma Sintering ◽  
New Process ◽  
Shape Memory Properties ◽  
Spark Plasma ◽  
Niti Shape Memory Alloys

The addition of Cu to near equiatomic NiTi shape memory alloys (SMAs) can provide some modifications of their shape memory properties by affecting their transformation behavior. The same effect was obtained in the case of Ni3Ti2 and Ni4Ti3 precipitates presence in the microstructure of NiTi. Also the substitution of Cu to NiTi alloys increases the hardness of the materials. This paper presents the microstructural and mechanical investigations of NiTi and NiTiCu alloys obtained by spark plasma sintering (SPS) process that represents a great potential for researchers as a new process for the fabrication of intermetallic compounds.

Abstract 19170: Lesion Morphological Classification by Optical Coherence Tomography to Predict Therapeutic Efficacy After Balloon Pulmonary Angioplasty

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Taku Inohara ◽  
Takashi Kawakami ◽  
Masaharu Kataoka ◽  
Keiichi Fukuda
Keyword(s):  
Optical Coherence Tomography ◽  
Therapeutic Efficacy ◽  
Pressure Ratio ◽  
Chronic Thromboembolic Pulmonary Hypertension ◽  
Thick Wall ◽  
Thin Wall ◽  
Optical Coherence ◽  
Pressure Wire ◽  
Balloon Pulmonary Angioplasty ◽  
Lesion Morphology

Introduction: Conventionally, angiographic classification has been used for chronic thromboembolic pulmonary hypertension (CTEPH). However, a classification based on lesion morphology is needed in the era of balloon pulmonary angioplasty (BPA). We sought to propose a classification of CTEPH based on lesion morphology detected by optical coherence tomography (OCT) and to evaluate its association with physiological stenosis assessed with a pressure wire and therapeutic efficacy in BPA. Methods: We analyzed 43 lesions in 17 patients who were treated with BPA under OCT and pressure-wire guidance from November 2012 to March 2015. OCT findings were classified into the following 4 categories: 1) mono-hole, 2) septum, 3) multi-hole with thin wall, and 4) multi-hole with thick wall. Results: Angiographic findings did not match the specific morphologic classification based on OCT findings. At the pre-BPA assessment, the pressure ratio of the septum type was significantly higher than that of the mono-hole and multi-hole with thick wall types (p = 0.026 and 0.047, respectively). Under the OCT-based classification, more than 50% of the septum and multi-hole with thin wall types could accomplish >0.8 of the mean pressure ratio assessed by a pressure wire, and these proportions were significantly higher than those of the other 2 types: mono-hole and multi-hole with thick wall (p = 0.044). Based on angiographic classification, accomplishment of this criterion was not significantly different among angiographic types. Conclusions: OCT-based morphologic lesion classifications in CTEPH were useful to predict whether the lesion stenosis could improve to the acceptable level mediated by BPA.

Study on Crashworthiness Characteristics of Several Concentric Thin Wall Tubes

2010 ◽  
Author(s):  
Parisa Hosseini Tehrani ◽  
Sajad Pirmohammad
Keyword(s):  
Finite Element ◽  
Optimum Combination ◽  
Thick Wall ◽  
Thin Wall ◽  
Finite Element Program ◽  
Linear Dynamic ◽  
Wall Structures ◽  
Moving Body ◽  
Oblique Loading ◽  
Element Program

There is a growing interest in the use of thin-wall structures as a means of absorbing the kinetic energy of a moving body. Multi-layered thin-wall structures are more efficient and lighter than thick-wall structures, and show better crashworthiness characteristics. In this task, several concentric aluminum thin wall tubes as energy absorber under axial and oblique loading are studied and optimum combination of these tubes is presented. The weight of the tubes is optimized while crashworthiness of tubes is not compromised. The commercial finite element program LS-DYNA that offers non-linear dynamic simulation capabilities was used in this study.

Effects of Compound Silicate Gangue on Mineral Composition and Microstructure of Sinter Produced by Baiyunebo Iron Ore Concentrates

2011 ◽  
Vol 194-196 ◽  
pp. 201-206
Author(s):  
Guo Ping Luo ◽  
Sheng Li Wu ◽  
Yi Ci Wang ◽  
Guang Jie Zhang ◽  
Zhi Zhong Hao ◽  
...  
Keyword(s):  
Mineral Composition ◽  
Iron Ore ◽  
Glassy Phase ◽  
Optical Microscope ◽  
Calcium Ferrite ◽  
Melting Time ◽  
Sintering Process ◽  
Test Device ◽  
Lower Melting Point ◽  
Mineral Compositions

The effects of compound silicate gangue on mineral composition and microstructure of sinter produced by Baiyunebo iron ore concentrates was studied by using mini-sintering test device and optical microscope. The result showed that compound silicate gangue has lower melting point, wider melting temperature range, longer melting time and melts easily to form glassiness during the sintering process. It can promote the solution of CaO and CaF2 in glassy phase, which affects viscosity and fluidity of glassy phase as well as the homogeneity of sinter microstructure. The compound silicate gangue intensely inhibits the generation of complex calcium ferrite and cuspidine as well. The major mineral compositions of sinter are hematite and glassy phase. The sinter exhibits multi-cavities and grainy structure when SiO2 exists entirely in the form of compound silicate gangue.

QUANTUM TUNNELLING OR THERMAL HOPPING

2000 ◽  
Vol 14 (19n20) ◽  
pp. 2109-2116
Author(s):  
N. PANCHAPAKESAN
Keyword(s):  
Quantum Tunneling ◽  
Condensed Matter ◽  
Order Term ◽  
Thick Wall ◽  
Thin Wall ◽  
Quantum Tunnelling ◽  
First Order ◽  
Classical State ◽  
Fourth Order Term ◽  
Loss Of Coherence

The nature of the transition from the quantum tunneling regime to the thermal hopping regime has importance in the study of condensed matter physics and cosmological phase transitions. It may also be of significance in collapse from quantum state to a classical state due to measurement (or loss of coherence due to some other process). We study this transition analytically in scalar field theory with a fourth order term. We obtain analytic bounce solutions which correctly give the action in thin and thick wall limits of the potential. We find that the transition is of the second order for the case of thick wall while it seems to be of first order for the case of thin wall.

Failure properties of 352 explanted silicone-gel breast implants

1996 ◽  
Vol 4 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Walter Peters ◽  
Dennis Smith ◽  
Stanley Lugowski
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Survival Curve ◽  
Breast Implants ◽  
Thick Wall ◽  
Thin Wall ◽  
Third Generation ◽  
Silicone Gel ◽  
Failure Properties

There have been three generations of silicone-gel breast implants. First generation implants (thick wall – thick gel with Dacron patches) were made from 1963 to 1972. Second generation implants (thin wall-thin gel) were made from 1972 until the mid 1980s. The introduction of third generation implants (stronger wall, low-bleed) was geographically dependent. In Canada, Dow Corning Silastic II implants were introduced in 1986, and Surgitek SCL implants were introduced in 1988. In the present study, a total of 352 silicone-gel breast implants were removed from 239 patients between 1981 and 1995. Their failure properties were dependent upon their generation (year of manufacture) and, for second generation implants, their duration in situ. Of the 352 implants, 20 were first generation, and all were fully intact. Twenty-eight were third generation implants, and 27 were fully intact. Failure properties of the 302 second generation implants were dependent upon their duration of implantation. A survival curve indicated that these implants began to fail (by leaking or rupturing) after four years in situ. By six years, 40% had failed. After 12 years, 95% had failed. Of the 171 second generation implants removed between 1991 and 1995, 77% had failed. The failure properties were similar for the three main manufacturers: Dow Corning, Heyer-Schulte and Surgitek. The failure rate for second generation implants is much higher than was previously believed. This is particularly significant in view of the current difficulty in diagnosing implant failure.

scholarly journals Optimum Design of Structural Parameters for Thin-walled Metal Container

2019 ◽  
Vol 288 ◽  
pp. 01007
Author(s):  
Liao Hongbo ◽  
Yang Dan ◽  
Yin Fenglong ◽  
Liang Xiaodong ◽  
Li Erkang ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Optimization Method ◽  
External Pressure ◽  
Test System ◽  
Manufacturing Cost ◽  
Thin Wall ◽  
Pressure Test ◽  
Critical Instability ◽  
Thin Walled ◽  
Better Than

In order to further increase the volume, reduce the weight and manufacturing cost, the key structural parameters of thin-walled metal packing container are optimized. The instability conditions under circumferential external pressure and axial load are analyzed, a mathematical model with the constraint of critical instability strength, the maximum volume and minimum mass as the objective is constructed. Multi-objective optimization method with nonlinear constraints is used to solve the key structural parameters, such as wall thickness, diameter and height, and the optimization result is calculated by fgoalattain() function in the Matlab optimization toolbox. The instability pressure test system is constructed, the instability pressure of the optimized thin-wall metal packing container is tested. The results show that the unstable pressure is higher than 120kPa, which are better than the design index.

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