Komarov laboratory mainly focusses on developing and designing eco-friendly materials and processes by applying physical fields, such as ultrasonic, electromagnetic fields, microwaves and plasma. And then elucidates the effects of these fields on the reaction kinetics, transport and interface phenomena.
  Specifically, investigations in these fields are being conducted(includes but not limited):
(1) minimization of chemical waste emission, (2) reduction of process temperature, (3) improvement of material recyclability.

Ultrasonic assited materials processing:Sonoprocessing

  The purpose of this resaerch is to design and develop a high-performance and durable large-scale ceramic sonotrodes for application in molten metal. The research includes the characterization of ceramic material, the simulation-based design of sonotrode shape, the fabrication of sonotrodes and investigation of characterization. The capacity of the sonotrodes to refine the grain structure has been examined by applying them to an industrial-scale DC caster at Nippon Light Metal Co.,ltd (NLM). The main characteristics of barbell-shaped sontrode are presented below.
  Life span of metallic sonotrodes in molten Al is also given for comparison (hours) : steel 0.3h; Ti alloy 2h; Nb-Mo heat resistant alloy 17h. Currently, the sonotrode is being investigated for application in strong acid and alkali condition. Besides, new types of ceramic sonotrodes are being designed in order to increase the efficiency of cavitation treatment.
ANSYS simulation(distribution of displacement within the sonotrode)

Sonotrode appearance

Main characteristics
Material Si3N4-based ceramics
(Nikkei seracompo S:Product of NLM)
Tip diameter 40~60 mm
Length 460~470 mm
Maximum amplitude
of tip vibration
60 μm(p-p)
Resonance frequency 19.5~20.5 kHz
Acoustic power 0.3~1.2 kW
Immerse depth 0.01~0.16 m
Maximum application temperature 800 ℃
Lifespan in molten Al > 700 hours
  Intermetallic compounds are a class of materials, which consist of two or more metallic elements. Intermetallic compounds usually have high hardness and brittleness. Some elements present as alloying elements or impurities in aluminum alloys, such as Fe, Mn, Cr, Zr and Ti, form coarse needle-shaped intermetallic compounds which are commonly detrimental to mechanical properties and formability of aluminum alloys. Although the effect of ultrasonic vibrations on the solidifying structure of aluminum alloys has been widely investigated, the data regarding effects of ultrasonic on behaviour of intermetallic compounds still remain conflicting. The available literatures reveal that ultrasonic vibrations can result in both refinement and coarsening of the intermetallic compounds.
  In this research, the synergistic effects of ultrasonic vibrations, acoustic streaming and temperature variation on the behaviour of various intermetallic compounds in molten aluminum alloys were investigated. The ultrasonic effects are discussed with an emphasis on heat and mass transfer during the nucleation and growth of intermetallic compounds in the melt.   It is well known that acoustic cavitation plays a decisive role in many ultrsonic-assisted technological processes, such as sonochemistry and ultrasonic casting of liquid metals. The cavitation produces tiny bubbles in the liquid, which then periodically implode, then generates violent bursts of pressure (or pulses) and high-intensive shock waves which are thought to contribute to the most of the ultrasonic effects. The other phenomenon that inevitably occurs during ultrasonic irradiation into fluids is acoustic streaming. Acoustic streaming is defined as a steady fluid motion, whihc is caused by the attenuation of ultrasonic waves in fluids due to the effects of lquid viscosity and heat conductivity. Acoustic streaming can cause both positive and negative effects on technological processes. Therefore, a proper understanding of acoustic streaming features is vital to consider while developing ultrasonic-assisted processes.
  In this research, both the acoustic cavitation and streaming in liquids were investigated with emphasis on the effects of sonotrode shape and vibration amplitude by water model experiments and numerical simulation. The research purpose is to find optimum conditions at which the negative influence of acoustic streaming can be effectively reduced.   Rotary Hearth Furnace (RHF) process is considered as one of the effective method to treat electric arc-furnace dust, partcularly for zinc recycling. In the traditional process, zinc is produced by reduction of zinc oxide from the dust, followed by vapor condensation in the gas phase. However, this process faces a number of problems, one of them being associated with a rapid clogging of filters by fine Zn-containing condensed particles and sticking of particles on inner walls of the exhaust gas duct of RHF.
  In this research, ultrasonic waves was applied to the exhaust gas loaded with Zn-containg particles in order to cause the particle agglomeration. Basically,fine particles could be forced to form agglomerates under application of sound waves according two mechanisms:orthokinetic collision and radiation pressure assisted acceleration.
  In this research, Zn sample was heated in a inductive furnace up to its vaporization temperature to produce Zn vapor and/or Zn particles which were carried up by Ar gas inside a vertical reactor. A 20kHz sonic was applied to the particles Ar carrier gas. Particle samples were collected from the top part of the reactor, and analyzed about particle size distribution, particle morphology and chemical composition. The effects of ultrasound pressure, Ag gas flow rate and temperature were also investigated. Results were discussed according to the mentioned mechanisms.