Growth Condition and Ferroelectric Property of Mn-Doped Na0.5K0.5NbO3 Crystal

2008 ◽  
Vol 388 ◽  
pp. 213-216 ◽  
Author(s):  
Yumi Inagaki ◽  
Kenichi Kakimoto ◽  
Hitoshi Ohsato
Keyword(s):  
Heat Treatment ◽  
Hysteresis Loop ◽  
Frequency Dependence ◽  
Cooling Rate ◽  
Growth Condition ◽  
Ferroelectric Property ◽  
Flux Method ◽  
Treatment Conditions ◽  
Mn Doped

Mn-doped Na0.5K0.5NbO3 (NKN) crystals have been grown by self-flux method under several heat-treatment conditions. The cooling rate affected the quality of Mn-doped NKN crystals significantly. When the cooling rate was 0.5 oC/min at temperatures ranging from 1050 to 950 oC, the synthesized Mn-doped NKN crystal exhibited a single nucleation growth, compared with multinucleation growth when the cooling rate was 0.25 oC/min at temperatures ranging from 1050 to 950 oC. The frequency dependence on the ferroelectric P-E hysteresis loop of the Mn-doped NKN crystal was not observed at measurement frequency of 0.1 – 25 Hz. The annealed 0.5 mol% Mn-doped NKN crystal exhibited excellent P-E hysteresis loop with Pr of 45.0 μC/cm2 and Ec of 7.2 kV/cm.

Effect of Temperature and Cooling Rate on the Microstructures of 35MnB and 25Mn Tubes during Heat Treatment

2016 ◽  
Vol 866 ◽  
pp. 196-200
Author(s):  
Sun Ho Jung ◽  
S. Lee ◽  
J. Lee
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Process Condition ◽  
Effect Of Temperature ◽  
Process Conditions ◽  
Optimal Process ◽  
Steel Tubes ◽  
Band Structures ◽  
Mechanical Quality

Band structures with pearlite and ferrite aligned as stripes can be created during the heat treatment of carbon steel. Since band structures undermine the mechanical quality of end products, it is highly important to select a process condition that will not create band structures as a result of heat treatment. This study verified the effect of temperature and cooling rate on the creation of band structures during heat treatment of 35MnB and 25Mn steel tubes for drive shafts and also considered the optimal process conditions to remove band structures or prevent their creation. The experimental results suggest that, during heat treatment of 35MnB and 25Mn steel tubes, it is most effective to ensure a cooling rate faster than furnace cooling in order to prevent band structures.

Fatigue Properties and Life Prediction of 8630 Cast Steel in the Presence of Weld Repair and Porosities

2013 ◽  
Author(s):  
Alireza Shirazi ◽  
Ihab Ragai
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Endurance Limit ◽  
Cast Steel ◽  
Fatigue Properties ◽  
Weld Repair ◽  
Treatment Conditions ◽  
Weld Material ◽  
Set Up

The objective of the this work is to study the effect of weld repair and macro-porosities on fatigue properties and fatigue life of AISI 8630 cast steel subjected to bending cyclic loads. Test specimens were cut from a cast steel component that contains macro-porosities. To regain the structural integrity, the component is typically excavated and weld repaired. In this study, weld repairs are simulated by machining a cylindrical groove across the width of the specimen then the groove is welded using different weld rods and various pre and post weld heat treatment conditions. All specimens were examined by radiography (X-Ray) in accordance with ASTM E446 before depositing the weld in order to verify the quality of the samples. After welding, the quality of the welded grooves was examined using ultrasonic testing (UT) and magnetic particle inspection (MPI) in accordance with ASTM A609 and ASTM E709 standards, respectively. Qualified samples were then machines to the final dimensions. The fatigue test was performed under pure bending conditions using four-point bend set up. This set up allows localizing stresses at the sites where weld repairs were applied. Experimental results show that specimens with stronger weld material tested under no heat treatment conditions have comparable fatigue performance to those heat treated specimens with lower strength weld material. Furthermore, it was found that the fatigue test results are highly affected by the presence of micro-porosities within the cast steel material. Therefore, an analytical approach to predict the fatigue life is also presented in this work. A good agreement is achieved between the predicted fatigue lives and the experimental results. Generally, the results show that for porosities with width to depth ratios between 0.25 to 1 and width size smaller than or equal to 1 mm the life is reduced by up to 1.5 orders of magnitude while the endurance limit was reduced by a factor of 1.57. Similarly for porosities with ratios between 1.5 and 2.5 and width greater than 1.5 mm the life was reduced by 2.5 orders of magnitude and the endurance limit was reduced by a factor of 2.2.

Centrifugal Casting Practice and Microstructure and Mechanical Properties of a 2205 Duplex Stainless Steel

2005 ◽  
Vol 475-479 ◽  
pp. 2527-2532 ◽  
Author(s):  
Sang Mok Lee ◽  
S. Yang ◽  
S.T. Kim ◽  
Y.S. Park ◽  
B.M. Moon
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Cooling Rate ◽  
Centrifugal Casting ◽  
Corrosion Properties ◽  
Σ Phase ◽  
Air Atmosphere ◽  
Treatment Conditions

Microstructural features, mechanical properties, and corrosion properties of a SAF2205 duplex stainless steel (DSS) were systematically investigated as functions of cooling rate during casting and heat treatment conditions. The choice of a duplex stainless steel was a SAF2205 alloy, of which composition is 0.03C, 21~23Cr, 4.5~6.5Ni, 2.5~3.5Mo, 0.08~0.2N, 1.0Si, and 2.0Mn with remaining Fe. A 5-stepped sand mold and the permanent Y-block mold were used to check the effect of cooling rate during solidification. The microstructural characteristics, such as grain size, the d/γ ratio, the existence of the carbides and σ phase has been noticed to greatly change with the variation of cooling rate during the casting procedure. Various heat treatment conditions were also examined to achieve the optimized mechanical properties of DSS. Based on the preliminary examination, the feasibility study of utilization of centrifugal casting has been carried out for the production of better quality DSS pipe components. Melting and casting practices of DSS during centrifugal casting in an air atmosphere were systematically investigated in order to obtain the optimized process parameters.

scholarly journals Investigation of Electrodeposited WO3 Film with Heat Treatment

2014 ◽  
Vol 17 (1) ◽  
pp. 029-032
Author(s):  
Yih-Min Yeh ◽  
Hsiang Chen
Keyword(s):  
Heat Treatment ◽  
Cyclic Voltammetry ◽  
Tin Oxide ◽  
Electrical Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Treatment Conditions ◽  
Deposited Film ◽  
Scanning Electron

In this research, we propose an alternative method to fabricate WO3 films as electro chromatic devices (ECDs). To fabricate the electrochromic film, we electrochemically deposit a WO3 film on FTO (fluorine-doped tin oxide). The deposited film was crystallized with heat treatment at various temperatures. To investigate the material quality of the film in different deposition and heat treatment conditions, X-ray diffraction (XRD) was used to examine the crystalline structure and scanning electron microscope (SEM) was used to analyze the surface morphology. Furthermore, the electrical performance of the film was evaluated by cyclic voltammetry (CV) and the transmittance modulation could still attain above 40% after 1000 times repeated cycles. The electrochromatic behavior has been demonstrated in WO3, electrodeposition, electrochromatic device, cyclic voltammetry, heat treatmentwavelength between 780 nm to 1050 nm.

Improving the Working Life of Steel Grinding Balls by Optimizing their Hardness and Tenacity

2014 ◽  
Vol 783-786 ◽  
pp. 2260-2265 ◽  
Author(s):  
Carlos Camurri ◽  
Claudia Carrasco ◽  
Rafael Colàs
Keyword(s):  
Heat Treatment ◽  
Central Zone ◽  
High Hardness ◽  
Working Life ◽  
Grinding Balls ◽  
Treatment Conditions ◽  
Internal Zone ◽  
New Treatment ◽  
Quenching Time

The carbon content in steel of the most produced grinding balls, 3 and 5 inch diameter, varies between 0.6% and 1.1% and, due to the presence of other addition elements, after their standard heat treatment, all the ball zones –external and central –reach high hardness values: over 60 RC in the case of the 3 inch diameter balls. The internal zone, hard and with low tenacity, produces a notorious diminution of the working life of the balls with respect to their theoretical potential. In this context, this work has as its objective to improve the quality of the grinding balls of 3 inch diameter, giving them highe r superficial hardness and a central zone with less martensite, and as a consequence, with moderate hardness and adequate tenacity. To perform this, the temperature time transformation (TTT) curves for the steel of the balls was determined by means of calorimetric (DSC) and metallographic analyses. Afterwards, a mathematical model (FDM) for the temperature distribution of the balls during their quenching and equalization treatment was done and experimentally validated. Along with the TTT curves and the math ematical temperature model, new heat treatment conditions were established: a reduced ball quenching time of 55 seconds (instead of the current 80 seconds), with a final central temperature of 500°C (instead of 273°C) and an equalization time of 200 seconds (instead of 40 seconds), and a final ball temperature of 203°C (instead of 139°C). With this new treatment, less martensite was obtained in the central zones of the balls, with an associate hardness on this area of 53-55 RC, while the standard hardness is maintained in their external zones.

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