Effect of Temperature on Induction Heating Deposited Monetite Coating on H2O2-Treated C/C Composites Treated by Alkaline Hydrothermal Method

2011 ◽  
Vol 66-68 ◽  
pp. 378-383
Author(s):  
Xin Bo Xiong ◽  
Cen Cen Chu ◽  
Jian Feng Huang

The effect of alkaline hydrothermal temperature on the transformation of induction heating deposited monetite coatings to hydroxyapatite coatings on the H2O2treated C/C composite was investigated. These monetite coatings were hydrothermally treated for 4h at 353K, 373K and 393K in a 50ml autoclave with 0.1M alkaline solution. After hydrothermal post-treatment, the structure, morphology and the chemical composition of these HA coatings were characterized with XRD, FTIR, SEM and EDS. A scratch test was conducted to measure the strength of the adhesion of the coatings to the HT-C/C substrate. The results showed that only part of hydroxyapatite phases at 393K could be transformed from the monetite coatings on HT-C/C substrate, while pure hydroxyapatite phases were observed to form in the as-converted coatings with critical loads of 45.9N and 51.1N respectively when the alkaline hydrothermal post-treatment treating temperatures were 353K and 373K. The reasons for these results were suggested.

2009 ◽  
Vol 16 (05) ◽  
pp. 675-681 ◽  
Author(s):  
DONG-MEI LI ◽  
XIN-BO XIONG ◽  
XIE-RONG ZENG ◽  
CHUN-LI ZOU ◽  
JI-ZHAO ZOU

Carbon/carbon composites with hydroxyapatite coatings are one of the attractive materials in the dental and orthopedic fields. In this study, hydrothermal treatment, in KOH aqueous and ammonia solutions, was used to convert an induction-heating-deposited monetite coating to an adherent HA coating on H2O2 treated C/C composites. The structure, morphology and chemical composition of the as-received HA coatings were characterized by XRD, FTIR, SEM and EDS. A scratch test was conducted to measure the adhesion of HA coatings to HT – C/C substrate. The results show that well-crystallized carbonate hydroxyapatite coatings could be achieved under the two reaction mediums. However, the as-obtained HA coatings after KOH hydrothermal treatment have higher crystallinity and Ca/P ratio than those after ammonia hydrothermal treatment, and reveal an average critical load of 29 N which is more than two times as high as that for HA coatings after ammonia hydrothermal treatment.


2014 ◽  
Vol 59 (1) ◽  
pp. 121-126
Author(s):  
M. Zygmunt-Kiper ◽  
L. Blaz ◽  
M. Sugamata

Abstract Mechanical alloying of high-purity aluminum and 10 wt.% NiO powders combined with powder vacuum compression and following hot extrusion method was used to produce an Al-NiO composite. Mechanical properties of as-extruded materials as well as the samples annealed at 823 K /6 h, were tested by compression at 293 K - 770 K. High mechanical properties of the material were attributed to the highly refined structure of the samples. It was found that the structure morphology was practically not changed during hot-compression tests. Therefore, the effect of deformation temperature on the hardness of as-deformed samples was very limited. The annealing of samples at 823 K/6 h induced a chemical reaction between NiO-particles and surrounding aluminum matrix. As a result, the development of very fine aluminum oxide and Al3Ni grains was observed.


1962 ◽  
Vol 84 (3) ◽  
pp. 223-257 ◽  
Author(s):  
F. Eberle ◽  
C. H. Anderson

The scales formed on seven ferritic and ten austenitic types of commercial tubing presently in use and of potential future use for superheater service were examined after 6, 12, and 18 months’ exposure to air and to flowing steam of 2000 psi at temperatures of 1100, 1200, 1350, and 1500 F. The effect of temperature and time of exposure on the adherence, thermal-shock resistance, thickness, structure, and chemical composition of the scales was investigated and the relative resistance to scaling of the various alloys evaluated.


Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1658
Author(s):  
Xiaochen Zhang ◽  
Zhijuan Yin ◽  
Bateer Buhe ◽  
Jiajie Wang ◽  
Lin Mao ◽  
...  

The effect of temperature on the corrosion resistance of layered double hydroxide (LDH) conversion coatings on AZ91D magnesium alloy, based on a closed-cycle system, was investigated. Scanning electron microscopy (SEM), photoelectron spectroscopy (XPS), and X-ray diffractometry (GAXRD) were used to study the surface morphology, chemical composition, and phase composition of the conversion coating. The corrosion resistance of the LDH conversion coating was determined through electropotentiometric polarisation curve and hydrogen evolution and immersion tests. The results showed that the conversion coating has the highest density and a more uniform, complete, and effective corrosion resistance at 50 °C. The chemical composition of the LDH conversion coating mainly comprises C, O, Mg, and Al, and the main phase is Mg6Al2(OH)16CO3·4H2O.


2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040031
Author(s):  
Stella Raynova ◽  
Khaled Alsharedah ◽  
Fei Yang ◽  
Leandro Bolzoni

A powder metallurgy approach was applied for the synthesis of an [Formula: see text] Ti-2Al-3Fe alloy. Blends of the elemental Ti, Al and Fe powders were compacted and subsequently sintered. High-frequency induction heating (HFIH) instead of conventional high-vacuum furnace heating was used for the sintering, due to its high efficiency. The effect of temperature on the level of densification, residual porosity and mechanical properties was studied. Electron dispersive spectrum analysis was used to study the dissolution and homogenization of the alloying elements. The results showed that a short induction sintering (IS) cycle in the range of 10–15 min is sufficient to achieve significant powder consolidation, evident by the increase of the density and mechanical properties. The residual porosity diminishes with the increase of the sintering temperature. Full dissolution of the alloying powders is completed after sintering at temperatures above those of [Formula: see text]- to [Formula: see text]-phase transformation.


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