scholarly journals Influence of Grain Refiners on the Wettability of Al2O3 Substrate by Aluminum Melt

2020 ◽  
Author(s):  
Jiawei Yang ◽  
Sarina Bao ◽  
Shahid Akhtar ◽  
Ping Shen ◽  
Yanjun Li
Keyword(s):  
Sessile Drop ◽  
Metal Substrate ◽  
Alumina Substrate ◽  
Ceramic Foam ◽  
Solidification Structure ◽  
Grain Refiner ◽  
Aluminum Melt ◽  
Substrate Interface ◽  
Master Alloys ◽  
Oxide Skin

AbstractIt is well known that grain refiner additions in aluminum melts significantly reduce the filtration efficiency of ceramic foam filters (CFF). However, the mechanism remains unclear. In this work, the influence of grain refiners on the wettability of alumina substrate by aluminum melt was studied by both conventional sessile drop and improved sessile drop methods at different temperatures and vacuums. Commercial purity aluminum (CP-Al) and grain refiner master alloys Al-3Ti-1B, Al-5Ti-1B, Al-3Ti-0.15C were used. It is found that master alloy melts wet alumina substrate better than CP-Al. Generally, a lower temperature or lower vacuum results in a higher contact angle. The roles of grain refiner particles in improving the wettability were studied by analyzing the solidification structure of post wetting-test droplets using SEM. Strong sedimentation of grain refiner particles at the metal-substrate interface was observed, which is attributed to the higher density of grain refiner particles compared to the Al melt. Meanwhile, a large fraction of grain refiner particles agglomerates at the oxide skin of the aluminum droplets, showing a strong adhesion between the particles and oxide skin. Such adhering of grain refiner particles is proposed to enhance the rupture of the original oxide skin of the droplets and slow down the reoxidation process at the surface layer. Both adherence of grain refiner particles to surface oxide skin and sedimentation of particles at the metal-substrate interface are responsible for the wetting improvement.

scholarly journals The Influences of Grain Refiner, Inclusion Level, and Filter Grade on the Filtration Performance of Aluminum Melt

2021 ◽  
Author(s):  
Jiawei Yang ◽  
Sarina Bao ◽  
Shahid Akhtar ◽  
Ulf Tundal ◽  
Stig Tjøtta ◽  
...  
Keyword(s):  
Oxide Films ◽  
Pilot Scale ◽  
Ceramic Foam ◽  
Grain Refiner ◽  
Filtration Process ◽  
Aluminum Melt ◽  
Filtration Performance ◽  
Master Alloys ◽  
Inclusion Level ◽  
High Level

AbstractThe addition of grain refiner particles in the aluminum melt is known to reduce the filtration efficiency of ceramic foam filter (CFF). In the present work, a systematic study on the influence of the addition level of Al-Ti-B master alloys and the inclusion level on the filtration performance of aluminum melt has been investigated by pilot-scale filtration tests using 50 PPi and 80 PPi filters. The inclusion level of the melt has been measured using both LiMCA and PoDFA. For 80 PPi CFF, the N20 inclusion (diameter larger than 20 μm) value in the post-filtrated melt does not increase when an ultra-high level of inclusions is introduced in the form of chips. For the melts with a low level of grain refiners (~ 0.5 kg/ton), the filtration performance of CFF is not affected by grain refiners, regardless of inclusion load. An addition of 2.0 kg/ton grain refiners reduces the filtration performance for melts with a high inclusion level, where post-filtration inclusions with the size of 15-20 µm were significantly increased. It is found, however, for the melts with an ultra-high inclusion load, the filtration performance of 80 PPi CFF is not affected by the grain refiner addition up to 2.0 kg/ton. The interactions between inclusions and grain refiner particles and the filtration mechanism have been studied by characterizing the spent filter and measuring the pressure drop during the filtration process. It is revealed that the strong adherence between oxide film with grain refiner particles dominates the grain refiner influence on the filtration performance of CFF. During the filtration process, oxide films have strong influences on the capturing of other inclusions such as oxide particles and TiB2 particles by the filter. A mechanism based on the interactions between oxide films and grain refiner particles is proposed to explain the CFF performance under the influence of grain refiner.

scholarly journals Effect of Inclusion and Filtration on Grain Refinement Efficiency of Aluminum Alloy

2022 ◽  
Author(s):  
Jiawei Yang ◽  
Yijiang Xu ◽  
Sarina Bao ◽  
Shahid Akhtar ◽  
Ulf Tundal ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Oxide Films ◽  
Pilot Scale ◽  
Ceramic Foam ◽  
Grain Refiner ◽  
Aluminum Melt ◽  
Refinement Efficiency ◽  
Master Alloys ◽  
And Performance

AbstractIt is well known that the filtration efficiency of ceramic foam filters (CFF) on aluminum melt can be significantly reduced by the addition of grain refiner particles under a high inclusion load. Also, it is usually considered that the filtration process has little impact on grain refinement efficiency. In this work, the influence of inclusions and filtration on the grain refinement effect of AA 6060 alloy has been studied. This was done through TP-1 type solidification experiments where the aluminum melt prior to and after the filter during a pilot-scale filtration test was investigated. In the experiments, 80 PPi CFFs were used to filtrate aluminum melt with an ultra-high inclusion load and two addition levels of Al–3Ti–1B master alloys. It is found that both inclusions and filtration significantly reduce the grain refinement efficiency of the grain refiner master alloys. A detailed characterization of the used filters shows that the reduction of grain refinement efficiency is due to the strong adherence of TiB2 particles to the oxide films, which are blocked by the CFF during filtration. A grain size prediction model based on deterministic nucleation mechanisms and dendritic growth kinetics has been applied to calculate the solidification grain size and estimate the loss of effective grain refiner particles during filtration. It is shown that due to the strong adherence between TiB2 particles and oxide films in the melt, the high addition level of aluminum chips also has an influence on reducing the grain refinement efficiency of aluminum melt without filtration. The results of this study extended our understanding of the behavior and performance of inoculant particles in CFF and their interactions with the inclusions.

scholarly journals Influence of Ceramic Foam Filters with Al2O3 Nanocoating on the Aluminum Filtration Behavior Tested With and Without Grain Refiner

2020 ◽  
Vol 51 (5) ◽  
pp. 2371-2380 ◽  
Author(s):  
Claudia Voigt ◽  
Beate Fankhänel ◽  
Björn Dietrich ◽  
Enrico Storti ◽  
Mark Badowski ◽  
...  
Keyword(s):  
Contact Angle ◽  
Sessile Drop ◽  
Industrial Applications ◽  
Thermomechanical Properties ◽  
Ceramic Foam ◽  
Grain Refiner ◽  
Filtration Performance ◽  
Filter Materials ◽  
Drop Tests

Abstract In industrial applications, filter materials are often chosen according to cost as well as their processing and thermomechanical properties, but rarely in terms of their behavior during filtration, which is largely due to there being insufficient information available on the influence of filter materials and surface quality on filtration behavior. In this study, the manufacture of functionalized Al2O3 nanofilters was investigated, along with their filtration performance in short- and long-term filtration trials. In addition, sessile drop tests were performed to measure the contact angle of the nanofunctionalized materials, and yielded an approximately 10 deg (11 pct) higher contact angle for nanocoated materials sintered at 800 °C and 1250 °C than for those sintered at 1600 °C and an approximately 23 deg (23 pct) higher contact angle compared to surfaces without a nanocoating. The filtration mechanism was assessed by means of Porous Disk Filtration Analysis (PoDFA) and Liquid Metal Cleanliness Analyzer (LiMCA) monitoring systems, as well as by analysis of the used and infiltrated filters using Scanning Electron Microscopy and Energy Dispersive X-ray analysis (SEM/EDX) technology. Both short-term and long-term filtration trials showed that the filtration behaviors of the reference and nanocoated filters were comparable. It was therefore determined that nanocoating of such filters with Al2O3 does not provide any improvement with regard to filtration performance.

scholarly journals The Interactions Between Oxide Film Inclusions and Inoculation Particles TiB2 in Aluminum Melt

2021 ◽  
Author(s):  
Jiawei Yang ◽  
Sarina Bao ◽  
Shahid Akhtar ◽  
Yanjun Li
Keyword(s):  
Grain Refinement ◽  
Master Alloy ◽  
Large Fraction ◽  
Oxide Films ◽  
Grain Refiner ◽  
Particle Sedimentation ◽  
Aluminum Melt ◽  
Refinement Efficiency ◽  
Long Time ◽  
Commercial Purity Aluminum

AbstractIn this work, a systematic study on the interactions between aluminum oxide films and TiB2 grain refiner particles and their effect on grain refinement behavior have been conducted. Oxide films were introduced into a commercial purity aluminum melt by adding AA 6061 alloy chips while the grain refiner particles were introduced by adding Al-3T-1B master alloy. Strong sedimentation of TiB2 grain refiner particles was observed in aluminum melt without chip addition during long-time settling. Most of the TiB2 particles were settled and accumulated at the bottom of crucible. In contrast, the sedimentation of TiB2 particles is much less in the melt with the addition of oxide films. A large fraction of TiB2 particles were found to be adhered to the oxide films located at the top part of the crucible, which inhibited the sedimentation of grain refiner particles. TP-1 type tests were also done to study the grain refinement efficiency of Al-3Ti-1B master alloy under different melt cleanliness and settling time. It is found that sedimentation of TiB2 particles greatly reduces the grain refinement efficiency. The introduction of oxide films seems to slightly alleviate the fading effect. This is owing to the strong adherence between the oxide films and TiB2 particles, which leads to a retardation of particle sedimentation.

scholarly journals Cavitation at filler metal/substrate interface during ultrasonic-assisted soldering. Part I: Cavitation characteristics

2018 ◽  
Vol 49 ◽  
pp. 249-259 ◽  
Author(s):  
Zhengwei Li ◽  
Zhiwu Xu ◽  
Lin Ma ◽  
Sheng Wang ◽  
Xuesong Liu ◽  
...  
Keyword(s):  
Filler Metal ◽  
Metal Substrate ◽  
Substrate Interface ◽  
Ultrasonic Assisted

scholarly journals Sn-Aided Joining of Cast Aluminum and Steel Through a Compound Casting Process

2021 ◽  
Author(s):  
Aina Opsal Bakke ◽  
Arne Nordmark ◽  
Lars Arnberg ◽  
Yanjun Li
Keyword(s):  
Reaction Layer ◽  
Sessile Drop ◽  
Liquid Aluminum ◽  
A356 Alloy ◽  
Casting Process ◽  
Bonding Layer ◽  
Cast Aluminum ◽  
Aluminum Melt ◽  
Compound Casting ◽  
Aluminum Oxide Layer

AbstractObtaining a strong bond between aluminum and steel is challenging due to poor wettability between aluminum melt and steel and brittle intermetallic phases forming in the interface. In this research, a novel coating method, namely hot dipping of Sn, has been developed to treat the steel insert surfaces. Results show that without preheating the mold or Sn-coated insert, a thin, crack-free, and continuous metallurgical bonding layer was achieved in the A356 aluminum/steel compound castings. Intermetallic structures forming in the interface have been characterized in detail. The Sn-coating layer completely melted and mixed with the liquid aluminum during the casting process. The reaction layer at the aluminum/steel interface is composed of ternary Al–Fe–Si particles and a thin layer of binary Al5Fe2 phase with thickness less than 1 µm. A small fraction of dispersed Sn-rich particles was observed distributing in the reaction layer and adjacent to eutectic Si particles in the A356 alloy. A sessile drop wetting test showed that Sn-coated steel substrates can be well wetted by aluminum melt. The improved wettability between A356 alloy melt and steel was attributed to the penetration and breaking of the aluminum oxide layer at the surface of the aluminum droplets by liquid Sn. Graphic Abstract

Novel Grain Refiner for Hypo- and Hyper-Eutectic Al-Si Alloys

2011 ◽  
Vol 690 ◽  
pp. 49-52 ◽  
Author(s):  
Magdalena Nowak ◽  
Nadendla Hari Babu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Al Alloys ◽  
Grain Structure ◽  
Grain Refiner ◽  
Silicon Alloys ◽  
Fine Grain ◽  
Cooling Conditions ◽  
Wide Range ◽  
Master Alloys

A novel effective grain refiner for hypo and hyper-eutectic Aluminium-Silicon alloys has been developed. The composition of the grain refiner has been optimized to produce a fine grain structure and finer eutectic. Effectiveness of grain size under various cooling conditions has also been investigated to simulate various practical casting conditions. For comparative purposes, a wide range of Al alloys have been produced with the addition of commercially available Al-5Ti-B master alloys. The results show that the addition of novel grain refiner reduces the grain size significantly. As a result of fine grains, the porosity in the solidified alloys is remarkably lower. A notable improvement in mechanical properties has also been observed.

scholarly journals Effect of Casting Temperature on Grain Size of Al-Si Alloys Refined by a Novel Grain Refiner

2014 ◽  
Vol 794-796 ◽  
pp. 77-82
Author(s):  
Leandro Bolzoni ◽  
Magdalena Nowak ◽  
N. Hari Babu
Keyword(s):  
Automotive Industry ◽  
Aluminium Alloys ◽  
Casting Temperature ◽  
Grain Refining ◽  
Grain Refiner ◽  
Casting Alloys ◽  
Primary Si ◽  
Structural Applications ◽  
Master Alloys ◽  
Mechanical Performances

The automotive industry is willing of employing a greater amount of light metals like aluminium, magnesium and titanium, in order to reduce the total weight of the cars and, consequently, fuel consumption. Even though some casting aluminium alloys are commonly employed for automotive structural applications, their mechanical performances can be improved by means of appropriate grain refining by heterogeneous nucleation. This practise is well established for wrought aluminium alloys by using Al-Ti-B master alloys but they are not effective in casting alloys due to the much higher silicon percentage (poisoning). A novel chemical composition which, actually, refines appropriately Al-Si alloys was developed at Brunel University. In this study the combined effect of casting temperature and addition of this novel grain refiner (NGR) on the microstructure of binary Al-Si alloys was considered. The addition of this NGR leads to the formation of finer primary α-Al grains, finer eutectic Al-Si intermetallics and less and smaller primary Si particles.

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