مکانیزم تشکیل رنگ در نانورنگدانه های سرامیکی

Colour performance of ceramic nano-pigments

مکانیزم تشکیل رنگ در نانورنگدانه های سرامیکی

ABSTRACT

Ceramic nano-pigments have been recently developed for ink-jet decoration of ceramic tiles using quadrichromic technology (cyan, magenta, yellow, and black colours). The colouring mechanisms and performance of CoAl2O4, Au, (Ti,Cr,Sb)O2 and CoFe2O4 nano-pigments were investigated by DRS, XRD and colorimetry. The nano-pigments were dispersed in several ceramic glazes and glassy coatings and their colour performance was compared with that of conventional micro-pigments. Each nano-pigment was characterized in terms of its colour mechanism and chemico-physical stability. Although the micro-pigments provided more saturated hues, intense colours were achievable in nano-pigments despite their very small particle size (<50 nm). Limitations to the use of nano-pigments arose for very high firing temperatures (>1200 °C) due to particle growth (e.g. Au) or dissolution in the glassy phase (e.g. titania).

 

رسوب نشانی لایه های نازک زیرکونیای پایدار شده با ایتریا

Yttria-stabilized zirconia thin films deposited by

pulsed-laser deposition and magnetron sputtering

رسوب نشانی لایه های نازک زیرکونیای پایدار شده با ایتریا،

به روش رسوب دهی لیزری پالسی  و کندوپاش ماگنترونی

ABSTRACT

Yttria-stabilized zirconia (YSZ, ZrO2:Y2O3) was deposited on (100) silicon by two physical vapor deposition techniques: pulsed laser deposition (PLD) and reactive magnetron sputtering (RMS). PLD thin films were grown on silicon substrates at 500 °C from the ablation of a 8YSZ ceramic target by a KrF excimer laser. RMS thin films were obtained by direct current magnetron sputtering of a Zr/Y metallic target in an oxygen/argon atmosphere. The deposition rate of the PLD technique using an UV excimer laser delivering pulses at a repetition rate of 40 Hz was found two orders of magnitude lower than the RMS method one. Both techniques led to the growth of crystalline films with a (111) preferential orientation. PLD films were dense and featureless whereas RMS ones exhibited well defined but compact columnar structure. Growth of a YSZ film of about 1 μm covering a rough and porous commercial anode support (NiO–YSZ cermet) was successfully carried out with both methods.

 

متالورژی منگنز -Manganese metallurgy

Manganese metallurgy review . Part I: Leaching of ores/secondary materials and

recovery of electrolytic/chemical manganese dioxide

مروری بر متالورژی منگنز. قسمت I: فروشویی سنگ‌های‌معدنی/مواد ثانویه

و بازیافت الکترولیتی/شیمیایی دی‌اکسید منگنز

ABSTRACT

The world rapidly growing demand for manganese hasmade it increasingly important to develop processes for economical recovery of manganese from low grade manganese ores and other secondary sources. Part I of this review outlines metallurgical processes for manganese production from various resources, particularly focusing on recent developments in direct hydrometallurgical leaching and recovery processes to identify potential sources of manganese and products which can be economically produced. 

High grade manganese ores (N40%) are typically processed into suitable metallic alloy forms by pyrometallurgical processes. Low grade manganese ores (b40%) are conventionally processed by pyrometallurgical reductive roasting or melting followed by hydrometallurgical processing for production of chemical manganese dioxide (CMD), electrolytic manganese (EM) or electrolytic manganese dioxide (EMD).

کامپوزیت‎های زمینه سرامیکی بافته شده

Multiscale model of woven ceramic matrix composites

considering manufacturing induced damage

کامپوزیت‎های زمینه سرامیکی بافته شده با توجه به آسیب‎های ایجاد شده‎ی تولید

ABSTRACT

Multiscale models play an important role in capturing the nonlinear response of woven carbon fiber reinforced ceramic matrix composites. In plain weave carbon fiber/silicon carbide (C/SiC) composites, for example, when microcracks form in the as-produced parts due to the mismatch in thermal properties between constituents, a multiscale thermoelastic framework can be used to capture the initial damage state of these composites. In this paper, a micromechanics-based multiscale model coupled with a thermoelastic progressive damage model is developed to simulate the elastic and damage behavior of a plain weave C/SiC composite system under thermal and mechanical loading conditions. The multiscale model is able to accurately predict composite behavior and serves as a valuable tool in investigating the physics of damage initiation and progression, in addition to the evolution of effective composite elastic moduli caused by temperature change and damage. The matrix damage initiation and progression is investigated at various length scales and the effects are demonstrated on the global composite behavior.

 جهت دانلود رایگان نسخه لاتین این مقاله اینجا کلیک کنید .

 

مواد سرامیکی و پلیمری دارای مواد رسانا

Conductor-Loaded Polymeric and ceramic Material

مواد سرامیکی و پلیمری دارای مواد رسانا (دارای ذرات تقویت کننده رسانا)

ABSTRACT

Conductor-filled polymers and ceramic are specific subsets of the conductor-Loaded dielectrics . The primary reason for adding conducting particles in polymers plastics or ceramics is to enhance the electrical conductance of the medium . In general polymers and ceramics when loaded with conductors become very good conductors of electricity and are useful in a wide range of electromagnetic applications. However inclusion of a metallic constituent in a polymer matrix may affect the low density and high strength or impact resistance properties of the plastics or the ceramics .

نانومرکب ­های سرامیکی برای چاپگرهای چهاررنگه جوهرافشان

Nano-sized Ceramic Inks for Drop-on-Demand Ink-Jet Printing in Quadrichromy

نانومرکب ­های سرامیکی برای چاپگرهای چهاررنگه جوهرافشان drop-on-demand (با فناوری چکانش روی موضع موردنظر)

ABSTRACT

Nano –sized ceramic inks suitable for ink –jet printing have been developed for the four-colours CMYK ( cyan ، magentah ، yellow ، black ) process . Nano- inks of different pigment composition ( Co _1-x O ، Au⁰ ،TiO₂ ، Sb ،Cr ،CoFe₂O₄ )  have been with various solid loading and their chemico-physical  properties ( particle size ، viscosity ، surface tension ، potential ) were tailored for the ink-jet application. The pigment particle size is in the 20-80 nm rang . All these nano-suspensions are stable for long time (i .e  several months ) due to either electrostatic ( high – potential values ) or steric stabilization mechanisms.

زیرکنیا

Zirconia

زیرکنیا

ABSTRACT

Zirconia is a very important industrial ceramic for structural applications because of its high toughness, which has proven to be superior to other ceramics. In addition, it has applications making use of its high ionic conductivity. The thermodynamically stable, room temperature form of zirconia is baddeleyite. However, this mineral is not used for the great majority of industrial applications of zirconia. The intermediate-temperature phase of zirconia, which has a tetragonal structure, can be stabilized at room temperature by the addition of modest amounts (below ∼۸ mol%) of dopants such as Y3+ and Ca2+. This doped zirconia has mechanical toughness values as high as 17 MPa • m1/2. On the other hand, the high-temperature phase of zirconia, which has a cubic structure, can be stabilized at room temperature by the addition of significant amounts (above ∼۸ mol%) of dopants. This form of zirconia has one of the highest ionic conductivity values associated with ceramics, allowing the use of the material in oxygen sensors and solid-oxide fuel cells. Research on this material actively continues and many improvements can be expected in the years to come.

اکسیدهای دیرگداز

Refractory Oxides

اکسیدهای دیرگداز

ABSTRACT

Refractory oxides encompass a broad range of unary, binary, and ternary ceramic compounds that can be used in structural, insulating, and other applications. The chemical bonds that provide cohesive energy to the crystalline solids also influence properties such as thermal expansion coefficient, thermal conductivity, elastic modulus, and heat capacity. This chapter provides a historical perspective on the use of refractory oxide materials, reviews applications for refractory oxides, overviews fundamental structure–property relations, describes typical processing routes, andsummarizes the properties of these materials.The term refractory refers to materials that are resistant to the effects of heat. Refractory oxides, therefore, are ceramic materials that can be used at elevated temperatures. These nondescript restrictions allow nearly any oxide to be classified as refractory. For this article, refractory oxides will refer, somewhat arbitrarily, to common crystalline compounds with melting temperatures of at least 1,800°C. These compounds can contain one or more metal or metalloid cations bonded to oxygen. As an introduction to the topic, this section provides a brief historic overview of materials commonly used in the refractories industry, including some lower melting temperature materials. The section also reviews some current trends in the industries that produce and use refractory oxides. The other sections of this chapter focus on phase-pure oxide ceramics that can be used at elevated temperatures.

مولایت

Mullite

مولایت

ABSTRACT

Mullite is the only stable intermediate phase in the alumina–silica system at atmospheric pressure. Although this solid solution phase is commonly found in human-made ceramics, only rarely does it occur as a natural mineral. Yet mullite is a major component of aluminosilicate ceramics and has been found in refractories and pottery dating back millennia. As the understanding of mullite matures, new uses are being found for this ancient material in the areas of electronics and optics, as well as in high temperature structural products. Many of its high temperature properties are superior to those of most other metal oxide compounds, including alumina. The chemical formula for mullite is deceptively simple: 3Al2O3 .۲SiO2. However, the phase stability, crystallography, and stoichiometry of this material remain controversial. For this reason, research and development of mullite is presented in an historical perspective that may prove useful to engineers and scientists who encounter this material under nonequilibrium conditions in their work. Emphasis is placed on reviewing studies where the primary goal was to create single-phase mullite monoliths with near theoretical density.