scholarly journals Release of Nanoparticles in the Environment and Catalytic Converters Ageing

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3406
Author(s):  
Sofía Navarro-Espinoza ◽  
Diana Meza-Figueroa ◽  
Roberto Guzmán ◽  
Alberto Duarte-Moller ◽  
Hilda Esparza-Ponce ◽  
...  
Keyword(s):  
Ultrafine Particles ◽  
Oxygen Vacancies ◽  
Xrd Analysis ◽  
Public Health Issue ◽  
Sintering Process ◽  
Particle Release ◽  
Cordierite Ceramic ◽  
Standard Operation ◽  
Main Effect ◽  
Three Way Catalyst

A Three-Way Catalyst (TWC) contains a cordierite ceramic monolith coated with a layer of Al2O3, CexZr1−xO2 and platinoids mixture. Under standard operation, the platinoid concentration decreases, exposing the remaining washcoat structure. After that particle release stage, the sintering process follows where the crystalline CexZr1−xO2 solution is broken and begins to separate into ZrO2 and CeO2 phases. ZrO2 is released to the environment as micro and nanoparticles, while a small amount of CeO2 generates a new AlxCe1−xO2 composite. The main effect of Ce capture is the growth in the size of the polycrystal structure from 86.13 ± 16.58 nm to 225.35 ± 69.51 nm. Moreover, a transformation of cordierite to mullite was identified by XRD analysis. Raman spectra showed that the oxygen vacancies (Vö) concentration decreased as CexZr1−xO2 phases separation occurred. The SEM-EDS revealed the incorporation of new spurious elements and microfractures favouring the detachment of the TWC support structure. The release of ultrafine particles is a consequence of catalytic devices overusing. The emission of refractory micro to nanocrystals to the atmosphere may represent an emerging public health issue underlining the importance of implementing strict worldwide regulations on regular TWCs replacement.

Direct Write Assembly of 3-Dimensional Structures with Aqueous-Based Piezoelectric Inks

2012 ◽  
Vol 512-515 ◽  
pp. 390-394 ◽  
Author(s):  
Ya Yun Li ◽  
Bo Li ◽  
Jing Bo Sun ◽  
Kun Peng Cai ◽  
Ji Zhou ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Xrd Analysis ◽  
Direct Write ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
3 Dimensional ◽  
Direct Ink Writing ◽  
Shaping Process ◽  
Piezoelectric Devices ◽  
Sintering Condition

A kind of aqueous based suspensions of lead lanthanum zirconnate titanate (PLZT) was developed for direct ink writing (DIW) assembly. Piezoelectric ceramic woodpile structures with diameter of 315-470μm were fabricated from these inks by using DIW. The preparation of aqueous based piezoelectric inks, the principle of DIW and the sintering process were systematically discussed. The ink with solids volume fraction over 70% by 1 day aging reveals shear-thinning behavior and proper viscoelastic properties, which ensures a feasible extrusion in the whole shaping process. The PLZT samples sintered at varying temperatures between 1150 oC and 1250 oC for 2h or 4 h in either air or a lead-rich atmosphere yielded various microstructures observed by scanning electron microscopy (SEM). Choosing the optimum sintering condition, the sintered products were densified with relative density exceed 98%. The test of X-ray diffraction (XRD) analysis reveals that the main phase of sintered samples is rhombohedral Pb0.93La0.07(Zr0.65Ti0.35)0.9825O3. The direct ink writing technique has advantages of good design ability and rapid forming capability, which opens up a potential route for the design and fabrication of piezoelectric devices.

scholarly journals Effects of Sintering Temperature Variation on Synthesis of Glass-Ceramic Phosphor Using Rice Husk Ash as Silica Source

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5413
Author(s):  
Rabiatul Adawiyah Abdul Wahab ◽  
Mohd Hafiz Mohd Zaid ◽  
Sidek Hj. Ab Aziz ◽  
Khamirul Amin Matori ◽  
Yap Wing Fen ◽  
...  
Keyword(s):  
Rice Husk ◽  
Glass Ceramic ◽  
Rice Husk Ash ◽  
Glass Ceramics ◽  
Xrd Analysis ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Silica Source ◽  
Quenching Method

In this study, the authors attempted to propose the very first study on fabrication and characterization of zinc-boro-silicate (ZBS) glass-ceramics derived from the ternary zinc-boro-silicate (ZnO)0.65(B2O3)0.15(RHA)0.2 glass system through a conventional melt-quenching method by incorporating rice husk ash (RHA) as the silica (SiO2) source, followed by a sintering process. Optimization of sintering condition has densified the sintered samples while embedded beta willemite (β-Zn2SiO4) and alpha willemite (α-Zn2SiO4) were proven in X-ray diffraction (XRD) analysis. Field emission scanning electron microscopy (FESEM) has shown the distribution of willemite crystals in rhombohedral shape crystals and successfully form closely-packed grains due to intense crystallization. The photoluminescence (PL) spectra of all sintered ZBS glasses presented various emission peaks at 425, 463, 487, 531, and 643 nm corresponded to violet, blue, green, and red emission, respectively. The correlation between the densification, phase transformation, microstructure, and photoluminescence of Zn2SiO4 glass-ceramic phosphor is discussed in detail.

Synthesis and Refinement of β-SiAlON by Nitriding and Post-Sintering of Si Mixture

2008 ◽  
Vol 403 ◽  
pp. 95-96
Author(s):  
Young Jo Park ◽  
Eun Ah Noh ◽  
Joong Ho Ahn ◽  
Hai Doo Kim
Keyword(s):  
Silicon Nitride ◽  
Liquid Phase ◽  
Transient Liquid Phase ◽  
Cost Effective ◽  
Xrd Analysis ◽  
Sintering Process ◽  
Reaction Bonding ◽  
Heating Up

A cost-effective route to synthesize β-SiAlONs from Si mixture by reaction bonding followed by post-sintering was investigated. Three different z values, 0.45, 0.92 and 1.87 in Si6-zAlzOzN8-z, without excess liquid phase were selected to elucidate the mechanism of both SiAlON formation and densification. For the RBSN(reaction-bonded silicon nitride) specimens, nitridation rate of more than 90% was achieved by multistep heating up to 1400oC in flowing 5%H2-95%N2 and residual Si was not detected by XRD analysis. Increase in density was observed with z values for the post-sintered specimens and this tendency was well explained by the presence of higher amount of transient liquid phase with larger z values. Measured z values of the synthesized -SiAlONs were nearly similar to calculated values using starting compositions. The slight deviation in the two z values was successfully explained by the reasonable assessment of nitriding and post-sintering process.

Synthesis and Characterization of Pb(Zr0.52Ti0.48)O3 Properties via High Planetary Mill

2017 ◽  
Vol 888 ◽  
pp. 96-102
Author(s):  
Shafiza Afzan Sharif ◽  
Julie Juliewatty Mohamed ◽  
Hasmaliza Mohamed ◽  
Zainal Arifin Ahmad ◽  
Wan Azhar Wan Yusoff
Keyword(s):  
Sintering Temperature ◽  
Xrd Analysis ◽  
High Energy ◽  
Planetary Mill ◽  
Firing Process ◽  
Material System ◽  
Sintering Process ◽  
Grain Growth Behavior ◽  
Sintering Condition

In this work, the piezoelectric material system of Pb (Zr0.52Ti0.48)O3 ceramics were synthesized by conventional solid state via high energy planetary mill reaction. This process were chosen in order to skip the calcinations and implement a single firing process which very effective to reduce the possibility of PbO loss. The effect of sintering parameters on structural behavior of pure PZT ceramic was discussed in detail. Comprehensive studies have been carried out in order get optimum parameter for sintering process, thus improved the performance of the pure PZT ceramics. Grain size properties of Pb (Zr0.52Ti0.48)O3 ceramics increased with increasing the sintering temperature and duration. However longer sintering condition (1200 °C, 3 hours) causes excessive PbO loss which leads to presence new phases in XRD analysis, promote grain growth behavior with inhomogenous microstructure and tend to have more pores.

Study on Electrolysis Performance of Bamboo Charcoal Bonded Grinding Wheel

2010 ◽  
Vol 135 ◽  
pp. 447-451
Author(s):  
Wei Li ◽  
Jian Wu ◽  
Bao Gong Geng
Keyword(s):  
Smooth Surface ◽  
Phenolic Resin ◽  
Xrd Analysis ◽  
Surface Generation ◽  
Grinding Wheel ◽  
Bamboo Charcoal ◽  
Sintering Process ◽  
Elid Grinding ◽  
Environmental Friendly ◽  
Hard And Brittle Materials

Electrolytic in-process dressing (ELID) Grinding was an effective machining method for gaining of super smooth surface for hard and brittle materials due to its excellent surface generation capabilities. Bamboo charcoal bonded (BCB) grinding wheel was an environmental friendly ELID grinding wheel which was made up of bamboo charcoal and phenolic resin as bonding agent with high temperature sintering process. In this paper, the electrolysis performances of the BCB grinding wheel with the different resin ratios were researched, and the surface of BCB grinding wheel formed a dense oxide layer in electrolysis action, was illustrated with SEM and XRD analysis.

Study on the Effect on Sintering Mineralization of Iron Ore

2013 ◽  
Vol 652-654 ◽  
pp. 2538-2542 ◽  
Author(s):  
Xiao Hui Fan ◽  
Ying Li ◽  
Xu Ling Chen
Keyword(s):  
Grain Size ◽  
Regression Analysis ◽  
Chemical Composition ◽  
Iron Ore ◽  
Raw Material ◽  
Sintering Process ◽  
Main Effect ◽  
Relationship Model ◽  
Ore Mineralization ◽  
The Relationship

The main effect on iron ore mineralization performance in the sintering process is the grain size of raw material and chemical composition. The results show that -0.5mm particles can mineralize, but +0.5mm particles remain a nucleus in sinter. This paper analyses the effect of the chemical composition on mineralization characteristics of liquid production. The relationship model is established by using regression analysis between the chemical composition and liquid formation characteristics. The mian factors of mineralization in the chemical composition: SiO2, CaO, MgO and Al2O3.

Spark Plasma Sintering of Silicon Nitride-Boron Carbide Composites

2008 ◽  
Vol 403 ◽  
pp. 225-226
Author(s):  
E. Ayas ◽  
A. Kalemtas ◽  
Gürsoy Arslan ◽  
Alpagut Kara ◽  
Ferhat Kara
Keyword(s):  
Electrical Resistivity ◽  
Spark Plasma Sintering ◽  
Xrd Analysis ◽  
Sintering Process ◽  
Electrically Conductive ◽  
Plasma Sintering ◽  
B4c Particles ◽  
Spark Plasma ◽  
In Situ Reactions

Si3N4-B4C composites containing fine and coarse B4C particles were produced using Al2O3 and Y2O3 as sintering additives via spark plasma sintering (SPS) technique. Phase assemblages of the produced composites were determined by XRD analysis. Si3N4, B4C and in situ formed SiC, h-BN and Si phases were observed. Even when incorporated in significant amounts, B4C was consumed readily in the Si3N4 based system. Consequently, full densification of these composites was found to be a very difficult task due to the simultaneous in-situ reactions, even in fast sintering process. Electrical resistivity measurements carried out at room temperature indicated that addition of both fine and coarse B4C particles decreased the electrical resistivity by several orders of magnitude due to the formation of electrically conductive in-situ phases, mainly SiC and metallic Si.

The Governance of Sintering Regimes on the Properties and Ageing Resistance of Y-TZP Ceramic

2012 ◽  
Vol 545 ◽  
pp. 81-87 ◽  
Author(s):  
Sivakumar Sivanesan ◽  
Ramesh Singh ◽  
Chin Kong Leong
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Phase Transformation ◽  
Low Temperature ◽  
Dwell Time ◽  
Superheated Steam ◽  
Xrd Analysis ◽  
Sintering Process ◽  
Monoclinic Symmetry ◽  
The Poor

The retention of nanometric microstructures is a challenge in any presureless sintering process. Grain size influences mechanical properties and grain coarsening retards densification upon sintering, thus resulting in the poor overall product properties. Hence, it is important to select, among others a suitable sintering regime which promotes densification and retards microstructure coarsening. In this work, Y-TZP ceramic bodies were fabricated under four different sintering regimes to investigate the governance of conventional Single-Stage Sintering (SSS) with 1 min and 2 h dwell time, and comparing their performance with bodies produced by Two-Stage Sintering (TSS). It was revealed that TSS sintered samples, yielded better properties than the SSS samples sintered at 1400°C with a dwell time of 2 hours. In the hydrothermal ageing test, TSS samples did not undergo the low-temperature degradation via the martensitic phase transformation of tetragonal to monoclinic symmetry. Nevertheless, it was found by XRD analysis that Y-TZP ceramics sintered by the SSS method using a short dwell time of 1 minute was effective in maintaining the tetragonal phase stability after 50 hours of exposure in superheated steam conditions.

scholarly journals Analysis of the electrical transport, conductivity and dielectric relaxation behavior of La0.75 Ba0.10 Sr0.15 Fe O2.875-δ (δ = 0.375 and 0.50) brownmillerite oxides

2021 ◽  
Author(s):  
Mariem Bouzayen ◽  
Radhia Dhahri ◽  
Meriem Saadi ◽  
Slaheddine Chaabouni ◽  
Kamel Khirouni ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Oxygen Vacancies ◽  
Electronic Conductivity ◽  
Electrical Conductance ◽  
Xrd Analysis ◽  
Dielectric Measurements ◽  
Low Dielectric ◽  
Semiconducting Properties ◽  
Current Voltage ◽  
Wide Range

Abstract The topotactic reduction of La0.75Ba0.10Sr0.15FeO2.875 with titanium metal leads to a new isostructural material of the composition La0.75Ba0.10Sr0.15FeO2.875−δ (δ = 0.375 and 0.50). XRD analysis of phases confirms that the obtained compound adopts a brownmillerite-type structure. A slight distorted monoclinic P2/m was found to describe the crystal structure. The transport properties have been investigated by current–voltage (I–V). The electric and dielectric measurements were carried out covering a wide range of temperature (300–600 K). Our materials display semiconducting properties as well as mixed ionic and electronic conductivity. At high temperatures, the activation energy values proved to be around 907 − 630 meV, which refers basically to oxygen vacancies conduction. The analysis of dielectric properties and dielectric losses (ε’, tanδ) of both compounds vs temperature at different frequencies demonstrates two relaxer attitudes. A low dielectric loss and low electrical conductance were displayed. Relying upon these values, these materials stand for perfect candidates for micro-electronics devices.

scholarly journals Experimental Investigation on Surface Roughness and Metal Removal Rate of Aluminium 2024 Alloy

2021 ◽  
Vol 9 (9) ◽  
pp. 1424-1429
Author(s):  
Dr. V. S. Srinivasa Murthy
Keyword(s):  
Surface Roughness ◽  
Metal Removal ◽  
Removal Rate ◽  
Xrd Analysis ◽  
Milling Machine ◽  
Cnc Milling ◽  
Sintering Process ◽  
Dimensional Changes ◽  
Cnc Milling Machine ◽  
2024 Alloy

Abstract: The purpose of this work is to investigate experimentally the surface roughness and MRR while machining of aluminium 2024 alloy which is prepared by powder metallurgical technique. Aluminium 2024 alloy prepared with different composition such as Pure Al, 1.5 W% of Mg and 2-6 % of Cu powders. Powders are blended with ball milling machine according to the composition required and specimens are prepared in square shape die (25*25mm) by applying uniaxial load of 200Mpa. The sintering process was performed at 594 0C for 60 min and cooled at room temperature. SEM and XRD analysis was carried out to know various characteristics like green density, dimensional changes during sintering, sintering density, mechanical properties and microstructures. Finally the Surface roughness and MRR during machining with CNC milling machine at different depth of cuts was also evaluated. Keywords: Aluminium 2024 alloy, surface roughness, MRR, SEM and XRD analysis

Sign in / Sign up

Export Citation Format

Share Document