scholarly journals Rapid Fabrication of High-Performance CaO-Based Integral Ceramic Mould by Stereolithography and Non-Aqueous Gelcasting

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 934 ◽  
Author(s):  
Qiang Yang ◽  
Weijun Zhu ◽  
Zhongliang Lu ◽  
Dichen Li ◽  
Zhongrui Wang ◽  
...  
Keyword(s):  
High Performance ◽  
Bending Strength ◽  
Gelation Time ◽  
Butyl Alcohol ◽  
Solid Loading ◽  
Green Body ◽  
Excellent Thermal Stability ◽  
Tert Butyl Alcohol ◽  
Rapid Fabrication ◽  
Monomer Content

A high-performance CaO-based integral ceramic mould was fabricated for investment casting by stereolithography (SLA) and non-aqueous gelcasting. The rheology of tert-butyl alcohol (TBA)-based CaO slurries and the effect of gelation parameters on the gelation time and strength of the green body were investigated to obtain a high-quality green body of the CaO-based integral ceramic mould. Then the pre-sintering and sintering processes were optimized to avoid cracks, reduce the sintering shrinkage, and improve the strength of CaO-based ceramic mould. The results showed that the CaO-based slurry with 56 vol % solid loading and 3 wt % dispersant content exhibited high stability and good flowability. The optimized gelation parameters were determined to be a monomer content of 20 wt %, a ratio of crosslinker to monomer of 0.06, an initiator content of 1 wt % and a gelation temperature of 40 °C. A reasonable sintering regime was identified to avoid cracks and guarantee a low shrinkage of 0.6%, a room temperature bending strength of 14.12 MPa and a high temperature (1200 °C) strength of 8.22 MPa. The CaO-based integral ceramic mould fabricated in this study has many advantages including excellent thermal stability, reaction-resistance to molten active alloys, ease of dissolution, and enhanced efficiency and economy in comparison to SiO2 or Al2O3 ceramic moulds.

scholarly journals The removal efficiencies and mechanism of aniline degradation by peroxydisulfate activated with magnetic Fe-Mn oxides composite

2021 ◽  
Author(s):  
Lin Qiao ◽  
Yu Shi ◽  
Qingli Cheng ◽  
Bingtao Liu ◽  
Jing Liu
Keyword(s):  
High Performance ◽  
Butyl Alcohol ◽  
Reactive Species ◽  
Precipitation Method ◽  
Oh Radicals ◽  
Liquid Chromatography Mass Spectrometry ◽  
Singlet Molecular Oxygen ◽  
Tert Butyl Alcohol ◽  
Co Precipitation ◽  
Mn Oxides

Abstract The Fe-Mn oxides composite prepared by a chemical co-precipitation method was used as a heterogenous peroxydisulfate catalyst for the decomposition of aniline. This study investigated the mechanism of aniline degradation by PDS activated with catalyst. Reactive species resulting in the degradation of aniline was investigated via radical quenching experiments with different scavengers, including methanol, tert-butyl alcohol, EDTA and sodium azide. Based on the experiments made here, it is speculated that the predominant reactive species responsible for the degradation of aniline may be holes and singlet molecular oxygen rather than SO4·− and ·OH radicals. The degradation of compounds in catalyst/peroxydisulfate system was put forward. The three possible intermediates were speculated by high performance liquid chromatography-mass spectrometry, and two possible degradation pathways were proposed.

Experimental Study on Drying Process of Green Body in Gelcasting of Metal Part

2012 ◽  
Vol 217-219 ◽  
pp. 1894-1898
Author(s):  
Hui Huang Liang ◽  
Fei Wang ◽  
Kai Yong Jiang
Keyword(s):  
Stainless Steel ◽  
Freeze Drying ◽  
316L Stainless Steel ◽  
Bending Strength ◽  
Fine Particles ◽  
Solid Loading ◽  
Green Body ◽  
Drying Process ◽  
Metal Part ◽  
Study Results

In this paper, gelatin was selected as binder, sodium alginate as dispersant. The slurries with low viscosity and high solid loading were prepared by mixing two types of 316L stainless steel powders with different particle sizes in proper mass ratios. The freeze drying process was adopted to treat the wet green body. The results show that the slurry with a solid loading as high as 58 vol.% can be obtained by mixing 316L stainless steel powders with mass ratio of fine particles to coarse as 4:6, which has better fluidity and densification. The viscosity of the slurry is less than 1Pa•s. After the freeze drying process, the bending strength of green body reaches 11.15MPa, the drying shrinkage is decreased to 0.44%, and the generation of crack can be prevented. The study results provide some helpful references for further research in rapid manufacturing of complex metal part.

Fabrication, Structure and Properties of Porous SiC Ceramics with High Porosity and High Strength

2010 ◽  
Vol 105-106 ◽  
pp. 608-611 ◽  
Author(s):  
Shao Feng Wang ◽  
Chang An Wang ◽  
Jia Lin Sun ◽  
Li Zhong Zhou ◽  
Yong Huang
Keyword(s):  
Compressive Strength ◽  
High Strength ◽  
Butyl Alcohol ◽  
Solid Loading ◽  
High Porosity ◽  
Reaction Bonding ◽  
Sintering Additive ◽  
Sic Ceramics ◽  
Tert Butyl Alcohol ◽  
Porous Sic

Porous SiC ceramics with high porosity and high strength were fabricated by gelcasting, with tert-butyl alcohol (TBA) as solvent, acrylamide (AM) as monomer, and in-situ reaction bonding with a-Al2O3 as sintering additive. SiC suspension with 10 vol% solid loading was successfully solidified by gel-casting to form high strength green body. The results showed that the compressive strength of the porous SiC ceramics increased with sintering temperature from 1300 to 1450°C, but porosity had little change, due to formation of more volume of cristobalite and mullite phases on the surface of SiC grains, accompanied by a large volume expansion effect. Very narrow single-peak distributions with about 2 mm median pore diameter could be found for the porous SiC ceramics. The porosity and compressive strength of the porous SiC ceramics sintered at 1450°C were 71.21 % and 12.14 MPa, respectively.

The Effects of Different Slurry on the Joining Characteristics of SiC Green Body

2012 ◽  
Vol 512-515 ◽  
pp. 411-414
Author(s):  
Yan Li Huo ◽  
Hai Lin Liu ◽  
Chun Peng Wang ◽  
Jie Tang ◽  
Yu Feng Chen ◽  
...  
Keyword(s):  
Grain Size ◽  
Binding Sites ◽  
Bending Strength ◽  
Solid Loading ◽  
Green Body ◽  
Gel Casting ◽  
Sic Ceramic ◽  
Welding Interface ◽  
Different Grain Size ◽  
Test Result

Experiments were carried out to join reaction-bonded silicon carbide (RBSC) ceramic in green body. SiC green bodies were fabricated by gel-casting method. The slurries for joint were prepared by different grain size of SiC. The results indicate the solid loading and the grain size of SiC influence the strength of welding. There is no clear welding interface between the two substrates in an appropriate solid volume loading and grain size. The average bending strength of welding after sintering can reach 300MPa. SEM was used to observe the cross-section morphology and microstructure of binding sites. The test result shows that its microstructure is similar to the RB-SiC ceramic. The mechanical properties of binding sites were tested. The result shows a desirable mechanical property.

Effects of Solid Content on Properties and Structure of PMN-PZT Green Body by Gelcasting

2013 ◽  
Vol 652-654 ◽  
pp. 367-370
Author(s):  
Ping Zhou ◽  
Jing Hong Du
Keyword(s):  
Piezoelectric Ceramic ◽  
Bending Strength ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Solid Content ◽  
Solid Loading ◽  
Green Density ◽  
Green Body ◽  
Microstructure And Properties ◽  
Uniform Microstructure

The piezoelectric ceramic of PMN-PZT was prepared by gelcasting using N-hydroxymothl acrylamide(NMAM) as monomer. The green bodies with different microstructure and properties were obtained by changing solid contents of slurry. The effects of solid volume fraction in slurries on properties of PMN-PZT green bodies were investigated. The results that green shrinkage reduced from 5.95% to 1.47%, the green density increased from 3.51g/cm3 to 4.69g/cm3, and green bending strength increased firstly then decreased when solid content of slurry changed from 45vol% to 60vol%. SEM photographs revealed thatSuperscript text the green body had a uniform microstructure and few agglomerates when the solid loading was 50vol%.

scholarly journals Effect of chopped ZrO2 fiber content on the microstructure and properties of CaO-based integral ceramic mold

2020 ◽  
Author(s):  
Qiang Yang ◽  
Fu Wang ◽  
Dichen Li
Keyword(s):  
Elevated Temperature ◽  
Bending Strength ◽  
Butyl Alcohol ◽  
Fiber Content ◽  
Ceramic Mold ◽  
Gel Casting ◽  
Ceramic Slurry ◽  
Filling Ability ◽  
Tert Butyl Alcohol ◽  
Sintering Shrinkage

Abstract A chopped ZrO2 fiber (ZrO2 (f)) reinforced CaO-based integral ceramic mold was successfully fabricated by stereolithography (SLA) and tert-butyl alcohol (TBA)-based gel-casting, and the effect of chopped ZrO2 (f) content on properties of the ceramic mold was investigated. The results show that the ZrO2 (f) content had a significant effect on the viscosity of CaO-based ceramic slurry, which directly affects the filling ability of the ceramic slurry in complex structures of the integral mold. The tiny structures of the ceramic mold cannot be filled completely with a ZrO2 (f) content exceed 3 vol%. When the content of ZrO2 (f) was 3 vol%, the ceramic slurry could meet the requirement of gel-casting with a viscosity of 0.84 Pa·s. The ZrO2 (f) content played an important role in tailoring properties of the ceramic mold, the sample fabricated with 3 vol% fiber content showed a harmonious microstructure and exhibited an excellent comprehensive performance with a room temperature (25 ºC) bending strength of 22.88 MPa, the elevated temperature bending strength (1200 ºC) of 15.74 MPa, the elevated temperature (1200 ºC) deflection of 0.86 mm and the sintering shrinkage of 0.40%, which can meet the requirements of casting very well.

scholarly journals Microstructure and mechanical properties of ZrB2-SiC composites fabricated by the centrifugal gel casting

2020 ◽  
Author(s):  
Jingmao Chen ◽  
Dongyang Zhang ◽  
Ping Hu ◽  
Shun Dong ◽  
Xinghong Zhang
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Ph Value ◽  
Ceramic Composites ◽  
Solid Loading ◽  
Pressureless Sintering ◽  
Gel Casting ◽  
Sic Ceramic ◽  
Monomer Content ◽  
Sic Composites

Abstract The high-performance and reliable ZrB2-SiC composites were fabricated by centrifugal gel casting and pressureless sintering. A well-dispersed ZrB2-SiC suspensions with up to 48 vol.% solid loading was achieved by adding 0.6 wt.% PAA dispersant and adjusting pH value to 11. The crack-free green ZrB2-SiC ceramic bodies with homogenous microstructure were prepared successfully by centrifugal gel casting with a relatively low monomer content of 3.5wt.% and centrifugal speed of 9000 r/min. After pressureless sintering at 2000 °C for 1 h, ZrB2-SiC composites with a relative density of 94.8%, a flexural strength of 394 ± 14 MPa and fracture toughness of 4.03 ± 0.10 MPa·m1/2 were achieved. This approach provided a promising colloidal processing to fabricate ceramic composites with reliable properties.

Preparation of Low Cost Ti-6Al-4V Alloy by Gelcasting

2012 ◽  
Vol 468-471 ◽  
pp. 2078-2081
Author(s):  
Qing Ye ◽  
Jun Jie Hao ◽  
Zhi Meng Guo ◽  
Min Chao Ru
Keyword(s):  
Relative Density ◽  
High Performance ◽  
Bending Strength ◽  
Low Cost ◽  
Morphological Properties ◽  
Green Body ◽  
High Solids ◽  
Rotating Electrode ◽  
Solids Loading ◽  
High Solids Loading

Ti-6Al-4V alloy was prepared by gelcasting. Plasma rotating electrode and hydrogenation-dehydrogenation Ti-6Al-4V powders were mixed used to meet both high performance and low cost objectives. The morphological properties were investigated by SEM. The results showed that the gelcasting green body with mixed powders has advantages of high solids loading and excellent sinterability. After sintered at 1400°C for 2h, the relative density reached 98%. The bending strength and hardness were 313MPa and 49.8(HRC).

scholarly journals Effect of Chopped ZrO2 Fiber Content on the Microstructure and Properties of CaO-Based Integral Ceramic Mold

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5398
Author(s):  
Qiang Yang ◽  
Fu Wang ◽  
Dichen Li
Keyword(s):  
Bending Strength ◽  
Butyl Alcohol ◽  
Fiber Content ◽  
Ceramic Mold ◽  
Complex Structures ◽  
Gel Casting ◽  
Ceramic Slurry ◽  
Filling Ability ◽  
Tert Butyl Alcohol ◽  
Sintering Shrinkage

A chopped ZrO2 fiber (ZrO2(f)) reinforced CaO-based integral ceramic mold was successfully fabricated by stereolithography (SLA) and tert-butyl alcohol (TBA)-based gel-casting, and the effect of chopped ZrO2(f) content on properties of the ceramic mold was investigated. The results show that the ZrO2(f) content had a significant effect on the viscosity of CaO-based ceramic slurry, which directly affects the filling ability of slurry in complex structures of the integral mold. The tiny structures of the ceramic mold cannot be filled completely with a ZrO2(f) content exceeding 3 vol %. The sample fabricated with 3 vol % fiber content showed a harmonious microstructure and exhibited an excellent comprehensive performance with 25 °C bending strength of 22.88 MPa, an 1200 °C bending strength of 15.74 MPa, a 1200 °C deflection of 0.86 mm, and a sintering shrinkage of 0.40%, which can meet the requirements of casting very well.

Thermodynamic and Kinetic Investigation of the Solvent Effect on the Oxidation of [Co(en)2SCH2COO]+ with S2O82- In Water-Methanol and Water-tert-Butyl Alcohol Mixtures

1993 ◽  
Vol 58 (5) ◽  
pp. 1001-1006 ◽  
Author(s):  
Oľga Vollárová ◽  
Ján Benko
Keyword(s):  
Transfer Functions ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Oxidation Of Co ◽  
Kinetics Of Oxidation ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Alcohol Mixtures ◽  
Kinetics Of

The kinetics of oxidation of [Co(en)2SCH2COO]+ with S2O82- was studied in water-methanol and water-tert-butyl alcohol mixtures. Changes in the reaction activation parameters ∆H≠ and ∆S≠ with varying concentration of the co-solvent depend on the kind of the latter, which points to a significant role of salvation effects. The solvation effect on the reaction is discussed based on a comparison of the transfer functions ∆Ht0, ∆St0 and ∆Gt0 for the initial and transition states with the changes in the activation parameters accompanying changes in the CO-solvent concentration. The transfer enthalpies of the reactant were obtained from calorimetric measurements.

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