Investigations on Interface Reactions and Wettability between Melt Superalloys and Ceramic Materials

2016 ◽  
Vol 703 ◽  
pp. 132-137 ◽  
Author(s):  
Xiao Yan Chen ◽  
Fei Li ◽  
Jun Wang ◽  
Bao De Sun
Keyword(s):  
Ceramic Material ◽  
Sessile Drop ◽  
Active Element ◽  
Interface Reaction ◽  
Ceramic Materials ◽  
Wetting Angle ◽  
Reactive System ◽  
Reaction Products ◽  
Interface Reactions ◽  
Sessile Drop Experiment

Interface reactions and wettability between melt superalloys and ceramic mould materials were investigated by using a sessile drop experiment. The wetting angle of the melt alloy on the ceramic material was calculated and the microstructure of the alloy interface was investigated by metalloscope as well as SEM. It was found that active element C in the alloy is an important factor that influences the interface reactions and the wettability. Alloys with C content lower than 0.07wt.% were almost stable on the ceramic material and no interface reaction products were found. However, alloys with C content higher than 0.16wt.% reacted with the ceramic materials. Purple reaction products were found on the alloy surface and sand adhesions were observed at the alloy-ceramic interface. In the non-reactive system, the wetting angle is in the range of 135o-150o. In the reactive system, the wetting angle is lower than 120o.

scholarly journals Interface Reactions Responsible for Run-Out in Active Brazing: Part 4

2022 ◽  
Vol 101 (1) ◽  
pp. 1-14
Author(s):  
PAUL T. VIANCO ◽  
◽  
CHARLES A. WALKER ◽  
DENNIS DE SMET ◽  
ALICE KILGO ◽  
...  
Keyword(s):  
Reaction Layer ◽  
Driving Force ◽  
Sessile Drop ◽  
Effective Means ◽  
Interface Reaction ◽  
Base Material ◽  
Test Sample ◽  
Interface Reactions ◽  
Braze Joint ◽  
Filler Metals

This study examined the interface reaction between Ag-xAl filler metals having x = 0.2, 0.5, or 1.0 wt-% and Kovar™ base materials. The present investigation used the braze joint test sample configuration. The brazing conditions were 965°C (1769°F), 5 min; 995°C (1823°F), 20 min, and a vacuum of 10–7 Torr. Run-out was absent from all test samples. Combining these results with those of the Part 2 study that used high-Al, Ag-xAl filler metals (x = 2.0, 5.0, and 10 wt-%) established these conditions for run-out: Ag-xAl filler metals having x ≥ 2.0 wt-% Al, which result in reaction layer compositions, and (Fe, Ni, Co)y Alz , having z ≥ 26 at.-% Al. The limited occurrences of run-out lobes resulted from the surface tension effect that quickly reduced the driving force for additional run-out events. The interface reactions were controlled by a driving force that was an expressed function of filler metal composition (Ag-xAl) and brazing temperature, as opposed to simply thermally activated rate kinetics. The differences of reaction layer composition and thickness confirmed that the interface reactions differed between the braze joint and sessile drop configurations. Collectively, the findings from the Parts 1–4 investigations concluded that the most-effective means to mitigate run-out is to place a barrier coating on the Kovar base material that will prevent formation of the (Fe, Ni, Co)y Alz reaction layer.

Interface Reaction between DD6 Single Crystal Superalloy and Ceramic Core

2021 ◽  
Vol 1035 ◽  
pp. 297-304
Author(s):  
Jian Sheng Yao ◽  
Long Pei Dong ◽  
Li Li Wang ◽  
Shu Yang ◽  
Wei Yang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Single Crystal ◽  
Interfacial Reaction ◽  
Interface Reaction ◽  
Ceramic Materials ◽  
Single Crystal Superalloy ◽  
Dense Layer ◽  
Ceramic Core ◽  
Interface Reactions ◽  
The Core

The interfacial reaction between alloys and ceramic materials is an important factor to influence the quality and service performance of the turbine blade. In this paper, three typical height sections of 120mm, 160mm and 210mm were selected, and the interface reactions between DD6 single crystal superalloy and silica based ceramic cores were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS). The results showed that the infiltration degree of the melt alloy increases with the increase of reaction time. The thickness of the reaction layer could be over 0.3mm when the reaction time increased up to 70min. The main reasons of forming the infiltration layer were the infiltration of the Al element and the interfacial reaction between the Al element and the ceramic core. There formed an aluminum deficient layer on the metal surface because of the interface reaction between the alloy and the ceramic core. The dense layer formed by interfacial reaction on the surface of the core will cause some difficulties for core leaching. Keywords: DD6 single crystal superalloy; Silica based ceramic core; Interface reaction

scholarly journals Investigation of Fused Alumina Based-Mold Facecoats for DZ22B Directionally Solidified Blades

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 606
Author(s):  
Fei Li ◽  
Hongjun Ni ◽  
Lixiang Yang ◽  
Yi Jiang ◽  
Donghong Wang ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Investment Casting ◽  
Sessile Drop ◽  
Directionally Solidified ◽  
Casting Method ◽  
Metallic Luster ◽  
Interface Reactions ◽  
Sessile Drop Experiment ◽  
Main Factor

The interaction between alloy melt and mold facecoats is the main factor affecting the surface quality of investment casting nickel-based superalloys. An investigation was undertaken to develop suitable refractories as facecoat materials for the directionally solidified blades of DZ22B nickel-based superalloys in order to avoid a sand-burning defect. The wettability and interface reactions between alloy melt and various facecoats were studied by using a sessile drop experiment and the real investment casting method, respectively. The results show that by adding Cr2O3 powder with the amounts of 2 wt.%, 5 wt.% and 10 wt.% in the fused alumina-based facecoats, the wetting angles between the alloy melt and facecoats decreased from 105.40° to 100.37°, 99.96° and 98.11°, respectively, while the sand-burning defect on the casting blade surfaces still formed during the process of directional solidification. However, by adding h-BN powder in the fused alumina-based facecoats, the wetting angles between the alloy melt and facecoats dramatically increased, the sand-burning defect on the casting blade surfaces was effectively inhibited and a metallic luster on the directionally solidified blades could be obviously observed. In this study, the suitable composition of mold facecoats for the investment casting of blades is 2 wt.% h-BN added fused alumina.

scholarly journals Interface Reactions Responsible for Run-Out in Active Brazing: Part 3

2021 ◽  
Vol 100 (12) ◽  
pp. 379-395
Author(s):  
PAUL T. VIANCO ◽  
◽  
CHARLES A. WALKER ◽  
DENNIS DE SMET ◽  
ALICE KILGO ◽  
...  
Keyword(s):  
Reaction Layer ◽  
Chemical Potential ◽  
Filler Metal ◽  
Sessile Drop ◽  
Interface Reaction ◽  
Base Material ◽  
Mitigation Strategies ◽  
Interface Reactions ◽  
Rate Kinetics ◽  
Sessile Drops

This study examined the interface reaction between sessile drops of the Ag-xAl filler metals having x = 0.2, 0.5, and 1.0 wt-% and KovarTM base material as an avenue to understand the run-out phenomenon observed in active filler metal braze joints. The brazing conditions were combinations of 965°C (1769°F) and 995°C (1823°F) temperatures and brazing times of 5 and 20 min. All brazing was performed in a vacuum of 10–7 Torr. Microanalysis confirmed that a reaction layer developed ahead of the filler metal to support spontaneous wetting and spreading activity. However, run-out was not observed with the sessile drops because the additional surface energy created by the sessile drop free surface constrained wetting and spreading. The value of z in the reaction layer composition, (Fe, Ni, Co)yAlz, increased with x of the Ag-xAl sessile drops for both brazing conditions. Generally, the values of z were lower for the more severe brazing conditions. Also, the reaction layer thickness increased with the Al concentration in the filler metal but did not increase with the severity of brazing conditions. These behaviors indicate that the interface reaction was controlled by the chemical potential rather than the rate kinetics of a thermally activated process. The determining metrics were filler metal composition (Ag-xAl) and brazing temperature. The findings of the present study provided several insights toward developing potential mitigation strategies to prevent run-out.

Numerical Modeling and Experimental Characterization of the Pyroplasticity in Ceramic Materials during Sintering

2010 ◽  
Vol 62 ◽  
pp. 203-208 ◽  
Author(s):  
Pasquale Bene ◽  
Danilo Bardaro ◽  
Daniela Bello ◽  
Orazio Manni
Keyword(s):  
Ceramic Material ◽  
Ceramic Materials ◽  
Constitutive Law ◽  
Beam Deflection ◽  
Firing Cycle ◽  
Experimental Characterization ◽  
Viscosity Increase ◽  
Ceramic Components ◽  
Deflection Theory ◽  
Sintering Shrinkage

The aim of the work is the study of the pyroplasticity in ceramic materials in order to simulate the deformations of complex ceramic component during sintering. A ceramic material undergoing densification can be treated as a linear viscous material. Generally, the viscosity decreases as the temperature increases, however the densification and the consequent grain growth, result in a viscosity increase. A bending creep test is proposed for measuring the change in viscosity of the ceramic material during densification. Equations, based on beam deflection theory, are derived to determine the viscosity during the whole firing cycle by measuring the deflection in the centre of specimens. In addition, dilatometric analyses are performed to measure the sintering shrinkage and the specimen density, which continuously changes during the sintering process. On the basis of an accurate experimental characterization the parameters of Maxwell viscoelastic constitutive law are derived. A numerical-experimental procedure has been adopted in order to calibrate the numerical model that, finally, has been used to predict the pyroplastic deformations of complex ceramic components.

Application of Focus-Variation Technique in the Analysis of Ceramic Chips

2019 ◽  
Vol 957 ◽  
pp. 187-194
Author(s):  
Roman Wdowik ◽  
Slawomir Swirad
Keyword(s):  
Machine Tool ◽  
Ceramic Material ◽  
Microscopic Study ◽  
Ceramic Materials ◽  
Software Tools ◽  
Milling Machine ◽  
Focus Variation ◽  
3D Scans ◽  
Physical Phenomena ◽  
Variation Technique

The paper presents the method of a microscopic study of ceramic chips which can be useful in the analysis of physical phenomena regarding machining of ceramic materials. The analyzed chips were obtained on the milling machine tool from the Al2O3 based ceramic material. The measurements were performed using focus-variation technique (FVT). The InfiniteFocus Real3D microscope from Alicona Imaging company was applied. The paper mainly focuses on the methodology of measurements and the application of microscope’s software tools which can be used in the analysis of chips' 3D scans. The conditions of measurement process are discussed on the basis of the results of exemplary measurements of ceramic chips.

scholarly journals Treatment of Soil Contaminated by Mining Activities to Prevent Contamination by Encapsulation in Ceramic Construction Materials

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6740
Author(s):  
Juan María Terrones-Saeta ◽  
Jorge Suárez-Macías ◽  
Antonio Bernardo-Sánchez ◽  
Laura Álvarez de Prado ◽  
Marta Menéndez Fernández ◽  
...  
Keyword(s):  
Ceramic Material ◽  
Contaminated Soil ◽  
Toxic Elements ◽  
Construction Materials ◽  
Well Being ◽  
Ceramic Materials ◽  
Potentially Toxic Elements ◽  
Raw Material ◽  
Mining District ◽  
Different Soils

Mining is an essential activity for obtaining materials necessary for the well-being and development of society. However, this activity produces important environmental impacts that must be controlled. More specifically, there are different soils near new or abandoned mining productions that have been contaminated with potentially toxic elements, and currently represent an important environmental problem. In this research, a contaminated soil from the mining district of Linares was studied for its use as a raw material for the conforming of ceramic materials, bricks, dedicated to construction. Firstly, the contaminated soil was chemically and physically characterized in order to evaluate its suitability. Subsequently, different families of samples were conformed with different percentages of clay and contaminated soil. Finally, the conformed ceramics were physically and mechanically characterized to examine the variation produced in the ceramic material by the incorporation of the contaminated soil. In addition, in this research, leachate tests were performed according to the TCLP method determining whether encapsulation of potentially toxic elements in the soil occurs. The results showed that all families of ceramic materials have acceptable physical properties, with a soil percentage of less than 80% being acceptable to obtain adequate mechanical properties and a maximum of 70% of contaminated soil to obtain acceptable leachate according to EPA regulations. Therefore, the maximum percentage of contaminated soil that can be incorporated into the ceramic material is 70% in order to comply with all standards. Consequently, this research not only avoids the contamination that contaminated soil can produce, but also valorizes this element as a raw material for new materials, avoiding the extraction of clay and reducing the environmental impact.

scholarly journals Effect of LiNbO3 on the Electrocaloric Performance of 0.94BNT-0.06BT Ceramic Materials

2021 ◽  
Author(s):  
Jing Chen ◽  
lei Wu ◽  
Luanfan Duan ◽  
Dongren Liu
Keyword(s):  
Ceramic Material ◽  
Room Temperature ◽  
Ceramic Materials ◽  
Adiabatic Temperature ◽  
Cooling Effect ◽  
Material System ◽  
Temperature Changes ◽  
Cooling Temperature ◽  
Temperature Range

Abstract Considering that the electric refrigeration temperature range of 0.94BNT-0.06BT ceramic materials is 100 ~ 140℃, the electric refrigeration performance of the 0.94BNT-0.06BT ceramic material system was modified by LiNbO3 doping to reduce the cooling temperature. As a result, the refrigeration temperature range of the 0.94BNT-0.06BT ceramic material system was lowered to 25 ~ 80℃, achieving its cooling effect near room temperature, and in this temperature range, the adiabatic temperature changes ∆T > 0.6K.

Preparation of Macroporous Ceramic Materials by Using Aluminium Powder as Foaming Agent

2014 ◽  
Vol 699 ◽  
pp. 336-341 ◽  
Author(s):  
Nurulfazielah Nasir ◽  
Ridhwan Jumaidin ◽  
Hady Efendy ◽  
Mohd Zulkefli Selamat ◽  
Goh Keat Beng ◽  
...  
Keyword(s):  
Ceramic Material ◽  
Reaction Rate ◽  
Porous Alumina ◽  
Porous Ceramic ◽  
Ceramic Materials ◽  
Calcium Sulphate ◽  
Alumina Ceramic ◽  
Deionized Water ◽  
Foaming Agent ◽  
Aluminium Powder

Aluminium powder was used as foaming agent in the production of macro-porous alumina ceramic. The porous ceramic material was developed by mixing an appropriate composition of cement, aluminium powder (Al), alumina (Al2O3), calcium oxide (CaO), gypsum (calcium sulphate dehydrate, CaSO4.2H2O), silica powder and deionized water. Different compositions of porous ceramic were produced at 2wt.%, 3wt.% and 4wt.% of aluminium powder. Their mechanical properties and macro-porosity structural of the porous ceramic material were analysed and compared. It is determined that the optimal properties of porous ceramic material were found at 3wt.% of aluminium powder and degraded drastically at 4wt.%. This phenomenon is due to the chemical reaction between the aluminium powder and DI water in which they form aluminium oxide that promotes the strength of the material but at the same time, more pores are created at higher reaction rate between these two fundamental materials.

Próteses parciais fixas metal free em região posterior – revisão da literatura considerando a longevidade, material cerâmico usado e principais falhas

2021 ◽  
Vol 12 (47) ◽  
pp. 113-125
Author(s):  
Nathalia Silveira Finck ◽  
Juliana da Mota Paiva ◽  
Rafael Dario Werneck ◽  
Mariana Itaborai Moreira Freitas ◽  
Priscilla Santos Guimarães
Keyword(s):  
Ceramic Material ◽  
Ceramic Materials ◽  
Inclusion Criteria ◽  
Electronic Library ◽  
Metal Free ◽  
Significant Difference ◽  
Bibliographical Survey ◽  
Observation Period

This study aimed to present a literature review with data obtained in vitro and in vivo on metal free partial fixed protheses (PFP) in the posterior region, considering the following variables: ceramic material to be used; prosthesis extension; survival or longevity; main failures found, and comparison with the longevity of conventional metaloceramic PFP. A bibliographical survey was carried out using the databases: United States National Library of Medicine (PubMed) and Scientific Electronic Library Online (Sciello) for articles in English and Portuguese from 1998 to 2019. Articles should meet the inclusion criteria, which were articles that contained information that enabled the calculation of PFPs survival and success, articles with a minimum observation period of 3 years, articles that identified the reason of failures, and studies reported since 1998. Sixteen studies met the inclusion criteria and were evaluated comparatively. The survival rate of the PFP’s varies depending on the ceramic material used and the prostheses extension, no significant difference was observed in the relation between the ceramic material used and the connectors size; however, the greater the extension of the prosthesis, the higher must be the connector size. It was concluded that ceramic materials based on zirconia are the ones that have the longest survival. In addition, the main reasons that lead to decreased survival of PFP’s are secondary caries and connector fracture, however, more studies are needed to determine safely which materials and the extent of PFP’s are the most indicated.

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