scholarly journals Preparation of a High-Performance Porous Ceramic Membrane by a Two-Step Coating Method and One-Step Sintering

2018 ◽  
Vol 9 (1) ◽  
pp. 52 ◽  
Author(s):  
Zhiwen Hu ◽  
Yulong Yang ◽  
Qibing Chang ◽  
Fengli Liu ◽  
Yongqing Wang ◽  
...  
Keyword(s):  
High Performance ◽  
Ceramic Membrane ◽  
Porous Ceramic ◽  
Ceramic Membranes ◽  
High Viscosity ◽  
Solid Content ◽  
Low Viscosity ◽  
Coating Method ◽  
One Step ◽  
Hole Defects

Hole defects and uneven membrane thicknesses can lead to poor performance, especially in the separation stability of ceramic membranes. This paper uses a one-step sintering method, which avoids hole defects and uneven membrane thicknesses, for the preparation of high-performance and defect-free ceramic membranes. For this purpose, two kinds of ceramic membrane slurry with high or low viscosities were prepared by alumina particles, as raw materials. Both the effects of the two coating process with a one-step coating method for low-viscosity slurry, and the two-step coating method with a high viscosity flush after a low viscosity coating, on the surface properties of a ceramic membrane, were studied in detail. The result shows that the properties of ceramic membranes can be improved by a two-step coating method, with a high viscosity flush after a low viscosity coating, A high-performance and defect-free ceramic membrane was obtained by one-step sintering at 1450 °C for 2 hr with 7 wt % solid content and a coating time of 11 s.

Mass Transfer in Tubular Ceramic Membranes for Polluted Water Treatment - Numerical Simulation

2018 ◽  
Vol 20 ◽  
pp. 16-33 ◽  
Author(s):  
J. Saraiva de Souza ◽  
S. José dos Santos Filho ◽  
Severino Rodrigues de Farias Neto ◽  
A.G. Barbosa de Lima ◽  
H.A. Luma Fernandes Magalhães
Keyword(s):  
Mass Transfer ◽  
Water Treatment ◽  
Produced Water ◽  
Ceramic Membrane ◽  
Porous Ceramic ◽  
Ceramic Membranes ◽  
Numerical Results ◽  
Polluted Water ◽  
Separation Processes ◽  
Water Separation

Innovative technologies are needed to attend the increasingly strict requirements for produced water treatment, since most of the separation processes are limited to particles larger than 10 μm. Separation processes using ceramic membranes are attracting great interest from academic and industrial community. Nevertheless, few studies, especially numerical, regarding the inorganic membrane’s application for the polluted water separation have been reported. In the present work, therefore, a study of fluid-flow dynamics for a laminar regime in porous tubes (tubular porous ceramic membrane) has been performed. The mass, momentum and mass transport conservation equations were solved with the aid of a structured mesh using ANSYS CFX commercial package. The velocity of local permeation was determined using the resistance in series model. The specific resistance of the polarized layer was obtained by Carman-Kozeny equation. The numerical results were evaluated and compared with the results available in the literature, where by a good agreement with each other was found. The numerical results, obtained by the proposed shell and tubular membrane separation module, indicate that there is facilitation of mass transfer and hence a reduction in the thickness of the polarized boundary layer occurs.

scholarly journals Enhanced Performance of Fly Ash-Based Supports for Low-Cost Ceramic Membranes with the Addition of Bauxite

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 711
Author(s):  
Wan Fan ◽  
Dong Zou ◽  
Jingrui Xu ◽  
Xianfu Chen ◽  
Minghui Qiu ◽  
...  
Keyword(s):  
Fly Ash ◽  
High Performance ◽  
Bending Strength ◽  
Ceramic Membrane ◽  
Sintering Temperature ◽  
Low Cost ◽  
Pure Water ◽  
Ceramic Membranes ◽  
Mullite Phase ◽  
Optimum Balance

Support is a necessary foundation for ceramic membranes to achieve high performance. Finding the optimum balance between high performance and low cost is still a significant challenge in the fabrication of ceramic supports. In this study, low-cost fly ash-based ceramic supports with enhanced performance were prepared by the addition of bauxite. The pore structure, mechanical strength, and shrinkage of fly ash/bauxite supports could be tuned by optimizing the bauxite content and sintering temperature. When the sintering temperature and bauxite content were controlled at 1300 °C and 40 wt%, respectively, the obtained membrane supports exhibited a high pure water permeance of approximately 5.36 m3·m−2·h−1·bar−1 and a high bending strength of approximately 69.6 MPa. At the same time, the optimized ceramic supports presented a typical mullite phase and excellent resistance to acid and alkali. This work provides a potential route for the preparation of ceramic membrane supports with characteristics of low cost and high performance.

A CASE STUDY OF BIOCOMPOSITE MATERIAL USE IN AUTOMOTIVE APPLICATIONS

2021 ◽  
Author(s):  
DANIEL WALCZYK ◽  
RONALD BUCINELL ◽  
STEVEN FLEISHMAN ◽  
SHARMAD JOSHI
Keyword(s):  
High Performance ◽  
Mechanical Performance ◽  
Flexural Modulus ◽  
Tensile Modulus ◽  
Maximum Tensile Stress ◽  
High Viscosity ◽  
Flexural Stress ◽  
Fiber Volume ◽  
Low Viscosity ◽  
Biocomposite Material

Interest in biocomposites is growing worldwide as companies that manufacture high-performance products seek out more sustainable material options. Although there is significant research on biocomposite material options and processing found in the literature from at least the last two decades, there are few experimentally based case studies published to help guide product designers and engineers when considering these materials. This paper discusses the use of biocomposites in the seat of an electric bus. Although it is clear that biocomposite material options are quite limited, the authors eventually settled on three natural reinforcements (cellulose, hemp, flax), two epoxies (one low and the other high viscosity) with high biobased carbon content, and one flax precoated with bioepoxy for consideration. Laminate plates with a 4mm nominal thickness are manufactured using VARTM (low viscosity epoxy only), hand layup as a surrogate for prepregging (high viscosity epoxy only), compression molding, and an out-of-autoclave process called the Pressure Focusing Layer (PFL) method. Permeability of the three reinforcements infused with the high viscosity epoxy and fiber volume fractions are determined experimentally to provide insight into VARTM processing and mechanical performance. The tensile modulus, maximum tensile stress, flexural modulus, and maximum flexural stress are measured for all combinations of reinforcement, resin, and processing using tension testing and three-point bending based on ASTM standards. Basic conclusions are drawn about the specific application and more generally about the process of using biocomposites in commercial products.

scholarly journals A Novel Organic–Inorganic Hybrid Admixture for Increasing Flowability and Reducing Viscosity of Ultra-High Performance Paste

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3385 ◽  
Author(s):  
Min Wang ◽  
Hao Yao
Keyword(s):  
Steric Hindrance ◽  
High Performance ◽  
High Performance Concrete ◽  
High Viscosity ◽  
Inorganic Hybrid ◽  
Oh Groups ◽  
Low Viscosity ◽  
Binder Ratio ◽  
The One ◽  
Water Binder Ratio

The low flowability and high viscosity of ultra-high performance concrete (UHPC), which is mainly caused by the silica fume (SF) agglomeration and low water–binder ratio, is a severe defect in its engineering applications. Herein, a novel organic–inorganic hybrid (OIH) admixture was synthesized by grafting comb-like polycarboxylate ether (PCE) onto the surface of SF. On the one hand, PCE-grafting could effectively prevent SF agglomeration and improve the dispersion of SF core. The reason being the consumption of polar silicon hydroxyl (Si-OH) groups on the surface of SF and the steric hindrance effect generated from PCE arms. On the other hand, OIH admixture could adsorb onto the surface of cement and SF particles by electrostatic interaction, exhibiting stronger steric hindrance effect than traditional comb-like PCE. As a result, UHPC system with this star-like OIH admixture presented high flowability and low viscosity at low water–binder ratio (0.18).

scholarly journals Preparation of high permeable alumina ceramic membrane with good separation performance via UV curing technique

RSC Advances ◽  
2018 ◽  
Vol 8 (24) ◽  
pp. 13567-13577 ◽  
Author(s):  
Yang Liu ◽  
Weiya Zhu ◽  
Kang Guan ◽  
Cheng Peng ◽  
Jianqing Wu
Keyword(s):  
Ceramic Membrane ◽  
Uv Curing ◽  
Ceramic Membranes ◽  
Dip Coating ◽  
Alumina Ceramic ◽  
Separation Performance ◽  
Good Separation ◽  
Drying Time ◽  
Coating Method ◽  
Dip Coating Method

The traditional dip-coating method for preparation of ceramic membranes requires a long drying time and easily produces drying defects. In this work, an improved dip-coating process was proposed.

Separation Performance of Nanostructured Ceramic Membranes: Analytical Model Development

2018 ◽  
Vol 43 (3) ◽  
pp. 245-253 ◽  
Author(s):  
Mashallah Rezakazemi ◽  
Saeed Shirazian
Keyword(s):  
Analytical Model ◽  
Ceramic Membrane ◽  
Porous Ceramic ◽  
Model Development ◽  
Ceramic Membranes ◽  
Hydrogen Gas ◽  
Separation Performance ◽  
Diffusivity Coefficient ◽  
Predictive Tool ◽  
Nanostructured Ceramic

AbstractNanostructured ceramic membranes have shown considerable separation performance. In this work, an analytical model is developed to evaluate the separation performance of porous ceramic membranes in gas separation applications. The model takes into account three layers, i. e., (1) active layer, (2) interlayer, and (3) support layer. For estimation of sorption at the interface of feed stream and membrane, the partition coefficient model was used and the unsteady-state conservation of mass equation coupled to molecular models of the diffusivity coefficient was used to predict the permeation of penetrant hydrogen gas through a ceramic membrane. It was observed that the model can be readily applied to other systems of interest as a predictive tool.

Incorporation of homogeneous Co3O4 into a nitrogen-doped carbon aerogel via a facile in situ synthesis method: implications for high performance asymmetric supercapacitors

2016 ◽  
Vol 4 (24) ◽  
pp. 9542-9554 ◽  
Author(s):  
Guanglin Sun ◽  
Liya Ma ◽  
Jiabing Ran ◽  
Xinyu Shen ◽  
Hua Tong
Keyword(s):  
High Performance ◽  
Synthesis Method ◽  
Carbon Aerogel ◽  
Drying Process ◽  
Asymmetric Supercapacitors ◽  
Nitrogen Doped ◽  
Coating Method ◽  
One Step ◽  
Nitrogen Doped Carbon

A novel high-performance electrode material, nitrogen-doped carbon aerogel/cobalt oxide (NCA/Co3O4) material, was prepared by a facile, one step and in situ coating method, followed by a freeze-drying process.

scholarly journals TRIBOLOGICAL BEHAVIOUR OF THE LOW AND HIGH VISCOSITY PEEK AGAINST STEEL USING DIFFERENTS CONTACT PRESSURES

2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Vanessa Rodriguez ◽  
Jacob Sukumaran ◽  
Yeczain Perez ◽  
Patrick De Baets ◽  
Matyas Ando
Keyword(s):  
High Performance ◽  
Friction And Wear ◽  
Large Scale ◽  
High Viscosity ◽  
Tribological Behaviour ◽  
Wear Performance ◽  
Low Viscosity ◽  
Enhanced Properties ◽  
Semi Solid ◽  
Contact Pressures

  In the market of polymers for tribological applications polyetheretherketone (PEEK) are often used for satisfying requests coming from industry regarding enhanced properties such as, thermal stability, friction and wear resistance. These properties promote the material to be used in so called high performance tribological applications. However, fundamental mechanisms governing friction and wear are not yet fully understood and neither is the influence of composition parameters. An important parameter is PEEK’s viscosity during manufacturing process which is heated up to semi-solid state, between its glass transition and melting temperature. This paper studies the friction and wear performance of low and high viscosity PEEK and pure PEEK under dry reciprocating sliding contact. The tests were performed in large scale specimens under flat-on-flat configuration to determine the transitions in tribological behaviour at different contact pressures. Tests were carried out at controlled atmosphere with 25 °C and a relative humidity of 50%. Contact pressures parameters were 4, 8 and 10 MPa used at a sliding speed of 20 mm/s. Post mortem analyses were carried out by means of 2-D surface topography and optical microscopy. The results show that the pure PEEK exhibits low coefficient of friction and wear rate when the contact pressure increase and similar behave for high and low viscosity PEEK.

Polyetherketone powder/epoxy blends with low viscosity and high mechanical properties

2020 ◽  
Vol 32 (9) ◽  
pp. 1052-1060
Author(s):  
Hong Li ◽  
Hang Su ◽  
Letian Wang ◽  
Lingyu Sun ◽  
Jiping Yang
Keyword(s):  
High Performance ◽  
Rheological Behaviour ◽  
Complex Viscosity ◽  
High Viscosity ◽  
Diglycidyl Ether ◽  
Forming Process ◽  
Low Viscosity ◽  
Lap Shear ◽  
Epoxy Blends ◽  
Insight Into

The difficult forming process and construction caused by high viscosity has been the main problem restricting the application of high-performance thermoplastic/epoxy blends. In this contribution, low viscous polyetherketone (PEK)/diglycidyl ether of bisphenol A epoxy resin (DGEBA) blends were prepared by mixing the ultrafine PEK powder and DGEBA monomer at ambient temperature. Rheological behaviour shows that complex viscosity of the undissolved blends containing 20 wt% PEK powder is two orders of magnitude lower than that of the dissolved one. Interestingly, diffusion and phase separation of PEK powder in the undissolved PEK/DGEBA/2-methylimidazole/dicyandiamide (M-DICY) blends are affected by the curing processes. Phase-inverted morphology was observed after curing at 120°C/1h + 160°C/0.5 h for the undissolved 20 wt% PEK/DGEBA/M-DICY blends which also exhibited outstanding tensile strength and lap shear strength both at 298 and 77 K. We believe this work should provide a new insight into the preparation of advanced thermoplastic/epoxy blends.

scholarly journals Fabrication and Characterization of Ice Templated Membrane Supports from Portland Cement

Membranes ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 93
Author(s):  
Amanmyrat Abdullayev ◽  
Paul H. Kamm ◽  
Maged F. Bekheet ◽  
Aleksander Gurlo
Keyword(s):  
High Temperature ◽  
Portland Cement ◽  
Ceramic Membrane ◽  
Porous Ceramic ◽  
Ceramic Membranes ◽  
Fabrication Process ◽  
Transmembrane Pressure ◽  
Hydration Reaction ◽  
Membrane Thickness ◽  
Membrane Fabrication

Porous ceramic membranes for aqueous microfiltration and ultrafiltration processes suffer from the high-costs of material and processing. The latter is mainly due to the high-temperature sintering step. In this work, cement-based membrane supports from ultrafine Portland cement are studied as a low-cost alternative to traditional oxidic ceramic supports. An environmentally friendly freeze-casting fabrication route is applied for the fabrication of porous membrane supports. Cement membrane supports are becoming mechanically stabile after hydration reaction of cement with water, which does not require any high-temperature sintering step as in a conventional ceramic membrane fabrication process. This fabrication route, which is sintering-free, decreases the cost and environmental impact of the membrane fabrication process by eliminating extra energy consumption step during sintering. The Archimedes method, scanning electron microscopy (SEM), micro-computed tomographic (µCT), and mercury porosimetry characterize the membrane supports in respect to open porosity, pore size distribution, morphology, and connectivity. The flexural strength of the 3 mm thick membranes is in the range from 1 to 6 MPa, as obtained by the ring-on-ring tests. The obtained membrane supports possess porosity in the range between 48 and 73% depending on fabrication conditions (cooling rate and the solid content, as determined by Archimedes method enabling water flux in the range between 79 and 180 L/(h·m2) at 0.5 bar transmembrane pressure difference and 3 mm membrane thickness.

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