Explore chapters and articles related to this topic
c Conductors: The Alloy Nb–Ti
Published in David A. Cardwell, David C. Larbalestier, Aleksander I. Braginski, Handbook of Superconductivity, 2023
Lance D. Cooley, Peter J. Lee, David C. Larbalestier
After the development of high-homogeneity alloys, substantial progress in understanding the interrelationship between precipitate amount and morphology was made. Increasing the heat treatment temperature increases the precipitation rate but also results in larger precipitates [4]. Similar results could also be obtained by increasing the heat treatment time at constant temperature. However, both routes tended to exacerbate barrier breakdown and promote mechanical instabilities. Increasing the number of heat treatments could be used to obtain similar results, as found by Li and Larbalestier [48] in Figure E3.7.10. For instance, [9] showed that short heat treatments (1–10 h) that are close together in strain (Δε ≈ 0.6) nucleate a large number density of precipitates. These later grow when a more aggressive heat treatment is applied at the final increment. The results of a wide variety of heat treatment parameters have been summarized in [2].
Chemistry in Wastewater Treatment
Published in Sreedevi Upadhyayula, Amita Chaudhary, Advanced Materials and Technologies for Wastewater Treatment, 2021
Sonali Sengupta, Chandan Kumar Pal
The precipitation process can be classified into two broad types: chemical precipitation and coprecipitation or adsorption. In chemical precipitation, pH, ionic equilibrium, and temperature are important factors. Exceeding the solubility product of cation and anion at favorable pH and temperature causes precipitation. Chemical precipitation proceeds through three stages: a) nucleation, b) crystal growth, and c) flocculation (9). Coprecipitation, or adsorption, is a process in which the normally soluble ions or contaminants in water, at the condition of precipitation, are adsorbed on the nuclei or crystals of solid precipitate and removed as a single phase with the precipitate.
Hydrogeochemical modeling to predict subsurface transport
Published in Domy C. Adriano, Alex K. Iskandar, Ishwar P. Murarka, Contamination of Groundwaters, 2020
Precipitation-dissolution is the process by which a chemical enters the aqueous phase or leaves to form a solid phase. The occurrence of trace metals in many solid phases of soil is an important influence on the aqueous concentration of these metals. The dissolution of unstable solid phases and the precipitation of stable phases work in concert to bound the amount of various substances in solution. The partitioning of metals between mobile and immobile forms is fundamental to the accurate simulation of a contaminant plume evolution. Factors that affect the precipitation-dissolution reactions are pH, type and concentration of complexing inorganic ligands, oxidation state of mineral components, temperature, and pressure.
The emergence of nanoporous materials in lung cancer therapy
Published in Science and Technology of Advanced Materials, 2022
Deepika Radhakrishnan, Shan Mohanan, Goeun Choi, Jin-Ho Choy, Steffi Tiburcius, Hoang Trung Trinh, Shankar Bolan, Nikki Verrills, Pradeep Tanwar, Ajay Karakoti, Ajayan Vinu
Another popular method for the synthesis of porous nanomaterials is the chemical precipitation method. In this method, a precipitate is obtained by the interaction of the dissolved precursors through a chemical reaction induced by chemical interaction between the reactants, usually aided by a precipitating agent. The particle size, pore size and structure can be controlled by the addition of surfactants in the solution. Using this approach, porous silicas were synthesised, wherein sodium silicate, ammonium chloride and CTAB were used as a silicon precursor, a precipitating agent and the porogen, respectively [135]. The porous hydroxyapatites with rod-shaped morphology and the particle size of ~10 × 50 nm in width and length were synthesised by this method, depicting the versatility of the method in achieving porosity with anisotropic shape [136]. Similarly, porous nano Nb2O5 modified with sponge-like and multi-folded nanostructures was also prepared using the chemical precipitation method [137]. These examples show the versatility of the chemical precipitation method in the synthesis of porous nanostructures with different chemical compositions, which could be used for drug delivery applications.
A review on solid base heterogeneous catalysts: preparation, characterization and applications
Published in Chemical Engineering Communications, 2022
Diksha K. Jambhulkar, Rajendra P. Ugwekar, Bharat A. Bhanvase, Divya P. Barai
In this method, material of interest is precipitated from a homogeneous mixture. Precipitation occurs due to change in temperature and addition of acidic and basic solutions. Several parameters which affect the precipitate are temperature, pH, raw materials composition, solvent, etc. Thus, formation of solid from liquid solution occurs in four stages (Ngamcharussrivichai et al. 2008):Precursor mixing and supersaturationNucleationCrystal growthAggregation
Accelerated age hardening response by in-situ ultrasonic aging of a WE43 alloy
Published in Materials and Manufacturing Processes, 2018
S. Palanivel, R. S. Mishra, R. E. Brennan, K. C. Cho
Precipitation rate depends on the thermodynamic driving force and, to a large extent, on the kinetics of the process. In cases where the diffusion of the solute is sluggish, aging at high temperature results in coarsening, while aging at low temperatures requires longer times. This holds true in the case of the WE43 (Mg-4Y-3Nd) alloy, where the solute atoms have sluggish diffusion rates in Mg. For example, at the aging temperature of 210°C, the diffusivity of Y and Nd are ∼10−19 and ∼10−21 m2/s, respectively [1, 2]. Such low values of diffusivity can be attributed to the larger size of Nd (182 pm) and Y (181 pm) atoms in comparison to Mg (160 pm). Since peak hardness is achieved in WE43 at lower temperatures (210°C) but requires longer aging times (48 hrs), any process that can aid in shortening the time to achieve maximum hardness is desirable.