Nijhuma Kayal

Bio: Nijhuma Kayal is an academic researcher from Central Glass and Ceramic Research Institute. The author has contributed to research in topics: Sintering & Porosity. The author has an hindex of 12, co-authored 49 publications receiving 441 citations. Previous affiliations of Nijhuma Kayal include Council of Scientific and Industrial Research.

Permeability and Nanoparticle Filtration Assessment of Cordierite-Bonded Porous SiC Ceramics

Abstract: Cordierite bonded porous SiC ceramics having pore fractions (e) between 0.33 and 0.72 and pore sizes of 6–50 μm, flexural strength of 5–54 MPa, and elastic modulus of 6–42 GPa were prepared by oxide bonding at 1350 °C in air compacts of SiC, Al2O3 and MgO powders with petroleum coke (PC) as the sacrificial pore former. To test the applicability of the porous ceramics in the fluid flow field, air permeation behavior was studied with fluid superficial velocity from 0.083 to 0.90 m s–1 and at 26–750 °C. The Darcian, k1, and the non-Darcian, k2, permeability coefficients were evaluated by fitting Forchheimer’s equation to the experimental results. The temperature dependence of the permeability coefficients was explained from structural changes occurring during test conditions. The collection efficiency of filter ceramics (e = 0.62–0.68) operating on removal of nanosized aerosol particles with sizes varying from 7 to 300 nm was determined by counting particles before and after filtration at a fluid superficial...

Evaluation of Air Permeation Behavior of Porous SiC Ceramics Synthesized by Oxidation-Bonding Technique

Abstract: Porous SiC ceramics were synthesized by oxidation bonding of compacts of commercial -SiC powder at 1300 degrees C. Different volume fractions of petroleum coke powder were used for variation of porosity of ceramics from 36% to 56%. The material exhibited variations of pore size from 3 to 15m, flexural strength from 5.5 to 29.5 MPa, and elastic modulus from 3.3 to 27.6 GPa. Air permeation behavior was studied at 26-650 degrees C. At room temperature Darcian (k(1)) and non-Darcian (k(2)) permeability parameters vary from 1.64 to 18.42x10(-13)m(2) and 0.58 to 2.95x10(-7)m, respectively. Temperature dependence of permeability was explained from structural changes occurring during test conditions.

Investigations on Material and Mechanical Properties, Air‐Permeation Behavior and Filtration Performance of Mullite‐Bonded Porous SiC Ceramics

Abstract: A theoretical relation between processing parameters and porosity (29–56%) of mullite-bonded porous SiC ceramics was derived and validated with experimental data. Porosity-dependent variation of fracture strength (9–34 MPa) and elastic modulus (7–28 GPa) was explained by the minimum solid area model. At room temperature, the Darcian, k1 (1.2 × 10−13–1.6 × 10−12 m2) and the non-Darcian, k2 (4.6 × 10−9–2.7 × 10−7 m) permeability coefficients showed linear variation with porosity. Tests conducted up to 650°C indicated an increase in k1 with temperature and a reverse trend for k2. Airborne NaCl nanoparticle filtration tests showed good performance of SiC ceramics with fractional collection efficiency of >99% at 46–56% porosity levels.

Porous ceramics: Light in weight but heavy in energy and environment technologies

Abstract: Benefitting from the combined properties of intrinsic ceramic materials and advanced porous configuration, lightweight porous ceramics with porosity ranging from 2.3 to 99% and pore size distribution within 3 nm - 3 mm exhibit low density, large specific surface area, high toughness, strong thermal shock resistance, good thermal insulation capability, excellent high temperature stability, and low dielectric constant, which are barely offered by metal, polymer or even their dense counterpart. This unique set of features endow porous ceramics an indispensable role in the future development of sustainable energy and environmental applications. To be successfully applied in these applications, precise selection of the type of ceramics and creation of their detailed structural features of the pores are the most important stages that require intensive investigations and comprehensive understanding. For a given ceramic, the synthesis process is critical for achieving the desired pore configuration and geometry which eventually determines the final properties of the products, including both the usual mechanical properties and other advanced functionalities. In this review, we will first focus on the fabrication processes that determine the pore structures and geometries. Four mainstream fabrication methods: partial sintering, replica template, sacrificial template, and direct foaming will be discussed, in addition to the additive manufacturing technique which has emerged as a promising process for the direct fabrication of porous ceramics components. Each approach demonstrates its unique suitability for a specific range of materials, porosity, pore size, pore connectivity, and pore distribution. The principles and challenges of each synthesis strategies will be summarised and discussed, the progress that can be made to meet the requirement of advanced applications has been clarified. We then focus on the properties derived from different pore features. The superior damage tolerance and thermal insulation capability of porous ceramics, as compared with their dense counterpart, are presented. Thirdly, the great potentials of these interesting porous ceramics for the energy- and environmental-based applications, including filters, catalyst support, energy storage and conversion components, energy harvesting devices, and insulators are highlighted, in association with the criteria and demands for manufacturing processes. It is envisaged that this review will provide a guidance in the manufacture of advanced porous ceramics with desired pore structures and properties tailored for specific applications. Finally, we will demonstrate how these porous ceramics could contribute to the development of current and future energy and environment technologies.

Tolerance of Iron-Deficient and -Toxic Soil Conditions in Rice.

Abstract: Iron (Fe) deficiency and toxicity are the most widely prevalent soil-related micronutrient disorders in rice (Oryza sativa L.). Progress in rice cultivars with improved tolerance has been hampered by a poor understanding of Fe availability in the soil, the transportation mechanism, and associated genetic factors for the tolerance of Fe toxicity soil (FTS) or Fe deficiency soil (FDS) conditions. In the past, through conventional breeding approaches, rice varieties were developed especially suitable for low- and high-pH soils, which indirectly helped the varieties to tolerate FTS and FDS conditions. Rice-Fe interactions in the external environment of soil, internal homeostasis, and transportation have been studied extensively in the past few decades. However, the molecular and physiological mechanisms of Fe uptake and transport need to be characterized in response to the tolerance of morpho-physiological traits under Fe-toxic and -deficient soil conditions, and these traits need to be well integrated into breeding programs. A deeper understanding of the several factors that influence Fe absorption, uptake, and transport from soil to root and above-ground organs under FDS and FTS is needed to develop tolerant rice cultivars with improved grain yield. Therefore, the objective of this review paper is to congregate the different phenotypic screening methodologies for prospecting tolerant rice varieties and their responsible genetic traits, and Fe homeostasis related to all the known quantitative trait loci (QTLs), genes, and transporters, which could offer enormous information to rice breeders and biotechnologists to develop rice cultivars tolerant of Fe toxicity or deficiency. The mechanism of Fe regulation and transport from soil to grain needs to be understood in a systematic manner along with the cascade of metabolomics steps that are involved in the development of rice varieties tolerant of FTS and FDS. Therefore, the integration of breeding with advanced genome sequencing and omics technologies allows for the fine-tuning of tolerant genotypes on the basis of molecular genetics, and the further identification of novel genes and transporters that are related to Fe regulation from FTS and FDS conditions is incredibly important to achieve further success in this aspect.