Colloidal processing of chemically prepared zinc oxide varistors. Part II: Near-net-shape forming and fired electrical properties

2004 ◽  
Vol 19 (5) ◽  
pp. 1341-1347 ◽  
Author(s):  
Nelson S. Bell ◽  
James A. Voigt ◽  
Bruce A. Tuttle ◽  
Duane B. Dimos
Keyword(s):  
Zinc Oxide ◽  
Slip Casting ◽  
Oxide Powders ◽  
Solids Loading ◽  
Density Values ◽  
Slip Cast ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Powder Compacts ◽  
Cast Parts

Chemically prepared zinc oxide powders were processed for the production of high aspect ratio varistor components (length/diameter >5). Near-net-shape casting methods including slip casting and agarose gelcasting were evaluated for effectiveness in achieving a uniform green microstructure that densifies to near theoretical values during sintering. The structure of the green parts was examined by mercury porisimetry. Agarose gelcasting produced green parts having low solids loading values and did not achieve high fired density. Isopressing the agarose cast parts after drying raised the fired density to greater than 95%, but the parts exhibited catastrophic shorting during electrical testing. Slip casting produced high green density parts, which exhibit high fired density values. The electrical characteristics of slip-cast parts are comparable with dry-pressed powder compacts.

scholarly journals Near net shape forming processes for chemically prepared zinc oxide varistors.

2005 ◽  
Author(s):  
Steven John Lockwood ◽  
James A. Voigt ◽  
Bruce Andrew Tuttle ◽  
Nelson Simmons Bell
Keyword(s):  
Zinc Oxide ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Zinc Oxide Varistors

Colloidal processing of chemically prepared zinc oxide varistors. Part I: Milling and dispersion of powder

2004 ◽  
Vol 19 (5) ◽  
pp. 1333-1340 ◽  
Author(s):  
Nelson S. Bell ◽  
Joe Cesarano ◽  
James A. Voigt ◽  
Steve J. Lockwood ◽  
Duane B. Dimos
Keyword(s):  
Zinc Oxide ◽  
Zeta Potential ◽  
Volume Fraction ◽  
Solid Phase ◽  
Companion Paper ◽  
Colloidal Processing ◽  
Oxide Powders ◽  
Solids Loading ◽  
High Solids Loading ◽  
Oscillatory Rheology

Chemically prepared zinc oxide powders are fabricated for the production of high aspect ratio varistor components. Colloidal processing was performed to reduce agglomerates to primary particles, form a high solids loading slurry, and prevent dopant migration. The milled and dispersed powder exhibited a viscoelastic to elastic behavioral transition at a volume loading of 43–46%. The origin of this transition was studied using acoustic spectroscopy, zeta potential measurements, and oscillatory rheology. The phenomenon occurs due to a volume fraction solids dependent reduction in the zeta potential of the solid phase. It is postulated to result from divalent ion binding within the polyelectrolyte dispersant chain and was mitigated using a polyethylene glycol plasticizing additive. This allowed for increased solids loading in the slurry and a green body fabrication study to be presented in our companion paper.

scholarly journals Antibacterial Characteristics of Heated Zinc Oxide Powders on Escherichia coli and Staphylococcus aureus.

1998 ◽  
pp. 633-636 ◽  
Author(s):  
Jun SAWAI ◽  
Osamu YAMAMOTO ◽  
Mikinori HOTTA ◽  
Hiromitsu KOJIMA ◽  
Tadashi SASAMOTO
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Zinc Oxide ◽  
Oxide Powders ◽  
And Staphylococcus Aureus

Aluminum-doped zinc oxide powders: synthesis, properties and application

2013 ◽  
Vol 25 (2) ◽  
pp. 678-692 ◽  
Author(s):  
P. Zhang ◽  
R. Y. Hong ◽  
Q. Chen ◽  
W. G. Feng ◽  
D. Badami
Keyword(s):  
Zinc Oxide ◽  
Oxide Powders ◽  
Synthesis Properties ◽  
Aluminum Doped Zinc Oxide

Mechanical Design for Accuracy of Linkage Servo Press for Near-Net Shape Forming

2018 ◽  
Author(s):  
Jing Tao ◽  
Huanan Qian ◽  
Suiran Yu
Keyword(s):  
Mechanical Design ◽  
Structure Design ◽  
Tolerance Allocation ◽  
Component Level ◽  
Eccentric Load ◽  
Servo Press ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Heavy Loads

The accuracy of machine is important to achieving highly accurate shapes. This paper is focused on mechanical design of highly accurate mechanical linkage servo press applicable to (near-)net shape forming. The effects of geometric errors, deformations under heavy loads and ram tilting are analyzed. A top-down design for accuracy approach is proposed: First, accuracy model for identification of inaccuracy-causing factors and their interlinking relations is developed. Then, based on this model, top accuracy index are decomposed and translated into structure design specifications at component level. Both analytic and simulation methods are employed for design for accuracy in aspects of dimensional and geometric tolerance allocation, stiffness synthesis and anti-eccentric load capability. A case study of mechanical design for accuracy of a six-linkage mechanical servo press is also presented to demonstrate and test the proposed design approaches.

Optical properties of zinc oxide powders

1979 ◽  
Vol 30 (1) ◽  
pp. 91-93
Author(s):  
M. M. Malov ◽  
V. P. Kutepova
Keyword(s):  
Zinc Oxide ◽  
Optical Properties ◽  
Oxide Powders

As-Cast Grain Size of Aluminum Alloys Refined by Al-Ti-B Master Alloys

2019 ◽  
Author(s):  
Mark Easton ◽  
David St John ◽  
Prasad Arvind
Keyword(s):  
Grain Size ◽  
Al Alloys ◽  
Good Ability ◽  
Refined Microstructure ◽  
Critical Technology ◽  
Master Alloys ◽  
Near Net Shape ◽  
Empirical Approaches ◽  
Cast Parts ◽  
Size Data

Grain refinement is a critical technology for the successful production of cast parts; whether that be preforms such as extrusion billet or rolling slab, or near net-shape castings. A refined microstructure has many advantages with reduced defects and improved mechanical properties. This article describes the approaches to the prediction of grain size in Al-alloys refined by Al-Ti-B master alloys. Included are empirical approaches based on the generation and analysis of grain size data, the development of analytical equations, and the use of finite element approaches to the prediction of grain sizes. It is clear that researchers have a good ability to predict grain size of Al-alloys grain refined by Al-Ti-B master alloys, although there are still some outstanding challenges, particularly in considering more extreme solidification conditions and poisoning of the master alloys.

scholarly journals Dense lanthanum silicate oxyapatite ceramics obtained by uniaxial pressing and slip casting

2018 ◽  
Vol 50 (4) ◽  
pp. 433-443
Author(s):  
Ramiro Toja ◽  
Nicolás Rendtorffa ◽  
Esteban Agliettia ◽  
Tetsuo Uchikoshi ◽  
Yoshio Sakka ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vickers Hardness ◽  
Growth Process ◽  
Slip Casting ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Oxygen Ion Conductivity ◽  
Oxygen Ion ◽  
Slip Cast ◽  
Lanthanum Silicate

Lanthanum silicate oxyapatite (LSO) is a promising ion conductive ceramic material, which has higher oxygen ion conductivity at intermediate temperatures (600-800?C) compared to yttria-stabilized zirconia. Its mechanical properties, though important for any of its applications, have been scarcely reported. In this study, we compare apparent densification, open porosity and Vickers hardness of samples conformed by uniaxial pressing and slip casting and fired up to 1600?C. Colloidal processing was optimized for slip casting in order to get high green densities. At sintering temperatures higher than 1400?C, both processing routes yielded comparable densities, although uniaxially pressed samples show slightly better mechanical properties, evidencing that slip cast ones already underwent a grain growth process.

Dispersion of Barium Ferrite Particles for Slip Casting in Magnetic Field

2006 ◽  
Vol 317-318 ◽  
pp. 143-146 ◽  
Author(s):  
Jing Long Li ◽  
Saburo Sano ◽  
Akihiro Tsuzuki ◽  
Akihiro Gotou ◽  
Yasuo Shibasaki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Polyethylene Glycol ◽  
Zeta Potential ◽  
Barium Ferrite ◽  
Slip Casting ◽  
Steric Repulsion ◽  
Ph Titration ◽  
Zeta Potentials ◽  
Water Based ◽  
Slip Cast

Water-based slurries containing barium ferrite particles have been prepared and slip cast in magnetic field. This paper presents the characteristics of the suspensions in terms of Iso-Electric Points (IEP) and zeta potential that were evaluated through pH titration and polymer adsorption. Both enlarging the specific surface area of particles by planetary milling and adjusting the pH to low value apparently increase the zeta potentials. Stable slurry was obtained by adding polyethylene glycol (PEG) into the suspension at pH = 2 ~ 3.5. The steric repulsion plays key role in dispersion and PEG films served as insulative layers and mechanically kept particles from contact each other. The barium ferrite particles formed many stacks of plates during slip casting, which either aligned randomly without magnetic field applied or regularly aligned to form textured structure when magnetic field was applied.

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