Room Temperature Impact Consolidation Research Articles

Electrochemical Properties of LiMn2O4-Li7La3Zr2O12 Composite Film Electrode Fabricated By Aerosol Deposition Method

LiMn2O4 (LMO)-Li7La3Zr2O12(LLZO) composite film electrode was successfully fabricated without any heat treatments by using aerosol deposition (AD) method. Mixture of 75wt%-LMO and 25wt%-LLZO powders with the averaged particle sizes around 1 μm was directly used as raw material. The mixed LMO and LLZO powders were sprayed onto a stainless steel substrate in deposition chamber evacuated to a low vacuum state below 10 Pa with N2 carrier gas for several 10 minutes. Mass flow of N2 carrier gas was set to be 20 L min-1 to form LMO-LLZ composite film via room temperature impact consolidation (RTIC). From both SEM observation and XRD measurement, it was found that as-deposited film has very dense structure without pores and is consisted from fractured LMO and LLZO crystalline particles with the sizes of several 10-100 nm. The thickness of composite film is 4 μm and LLZO content in the film was estimated to be around 21wt%. LMO-LLZO composite film electrode showed good electrochemical property in liquid electrolyte and higher discharge capacity than LMO film without including LLZO. The discharge capacities reduced by the weight of LMO-LLZO composite film electrode was 70 mAh g-1, 62 mAh g-1 and 55 mAh g-1 at different discharge current rates of 0.07C, 0.7C and 3C (1C = 0.11 mA cm-2). They are corresponding to the specific capacity per LMO in the film of 90 mAh g-1, 80 mAh g-1 and 71 mAh g-1, respectively. In addition, the LMO-LLZO composite film electrode showed good capacity retention during cycle testing, which is attributed to strong adhesion between the composite film and substrate by AD. The present results suggest that AD method can potentially be used for electrode layer composed of active material and solid electrolyte for all-solid state lithium-ion battery.

Characterization of as-deposited Li4Ti5O12 thin film electrode prepared by aerosol deposition method

We successfully fabricated lithium titanate Li4Ti5O12 (LTO) thin film electrode at room temperature by aerosol deposition (AD) method. Agglomerated LTO powder with the size of 5–6 μm composed of primary sub-micron particles was used as raw material and deposited directly on a stainless steel substrate via room temperature impact consolidation (RTIC). X-ray diffraction patterns revealed that as-deposited LTO film has a same crystalline structure with raw powder and no secondary phases were formed during the deposition process. SEM observation showed that the film has porous structure consisted from LTO particles with the sizes of several 100 nm. As-deposited LTO film electrode showed good electrochemical property in liquid electrolyte. The discharge capacities of 159 mAh g−1 and 125 mAh g−1 were obtained at current density of 0.067 mA cm−2 (=0.5C rate) and 2.68 mA cm−2 (=20C rate). The former corresponds to 91% of theoretical capacity for LTO (=175 mAh g−1). The film electrode also showed good capacity retention, indicating that adhesion between the film and substrate are sufficiently strong.

Evaluation of TiO<sub>2</sub> Films Fabricated by Aerosol Deposition

Films of titanium dioxide (TiO2) were deposited by aerosol deposition at room temperature. Anatase TiO2 powders were used. The crystal structure of these films was a mixture of the anatase and brookite TiO2 phases, while the rutile TiO2 phase was observed at high carrier gas flow rates. The TiO2 film thickness increased in proportion with the scan time and the carrier gas flow rate. Film thickness was constant at constant total deposition times. Flake-like and mesh-like surface morphologies were observed on the films. The direct-current resistivity was estimated from the dielectric constant and the loss tangent; it was found to be much smaller than that of bulk TiO2. We speculate that this low resistivity is due to reduction of TiO2 particles during room-temperature impact consolidation in a N2 atmosphere.

常温衝撃固化現象とエアロゾルデポジション（AD）法によるセラミックスコーティング

常温衝撃固化現象とエアロゾルデポジション（AD）法によるセラミックスコーティング

Room Temperature Impact Consolidation (RTIC) of Fine Ceramic Powder by Aerosol Deposition Method and Applications to Microdevices

Ceramic integration technology requires downsizing and/or improvement of device performance in many applications, such as in the fabrication of microelectromechanical systems, display devises, fuel cells, optical devices, and RF components. For these applications, realization of high-speed deposition rate, low process temperature, and fine patterning in ceramic coating are very important. The aerosol deposition (AD) method has many advantages for above requirements in comparison with conventional thin-film method or thermal spray coating technology. In this article, advantages of the AD method are highlighted by realizing a comparison with conventional thin-film methods and thermal spray technology. Challenges associated with AD method are also highlighted. At the end, examples of integration of AD method in the fabrication of electronic components are also given to show the easiness in usage and in integration of this method in the device process flow.

Blocking Characteristic of Aerosol Deposited Alumina on Plastics against Liquid

Aerosol deposition, based on room temperature impact consolidation (RTIC), can form aluminum oxide films on some of the plastics. However the characteristics of these films are not yet known much. One of the important characteristics of ceramic films on plastics is to block liquid to protect the plastic substrates. This may also give information on the structures of aerosol deposited films on plastics. So blocking characteristic of aerosol deposited aluminum oxide films on polycarbonate plates was evaluated with liquid acetone. Polycarbonate becomes clouded when liquid acetone is poured on. Therefore the state of substrate polycarbonate can show whether the aluminum oxide films effectively blocked the liquid by pouring acetone on the films. The aerosol deposited thin aluminum oxide films could not block acetone, and the whole area covered by acetone becomes clouded. In thicker films the residual stress in the films cause many cracks initiated from attacked points by acetone and frequently aluminum oxide films were peeled off from polycarbonate substrates. When the thickness is over lO~m, the films could block acetone. This suggests the existence of minute pores in the aerosol deposited films on plastic substrates.

MICROSTRUCTURE OF CERAMIC THICK FILM FORMED BY AEROSOL DEPOSITION AND ITS APPLICATIONS TO MICROACTUATOR

ABSTRACT Microstructure of PZT thick layer formed on strain steel substrate via a room temperature impact consolidation (RTIC) of fine ceramic powder using Aerosol Deposition (AD) with post heat treatment were investigated in order to fabricate a micro actuator. An optical micro scanner, having a high speed performance with a resonance frequency of over 20 kHz and scan angle of over 20 degree in atmospheric ambient, was successfully fabricated. The piezoelectric thick layer was directly deposited onto the metal scanner structure, which was fabricated by mechanical punching. This method is a powerful tool to realize ceramic integration with metal components.

粒子積層プロセスの新しいトレンド エアロゾルデポジション法による常温衝撃固化現象とその応用

粒子積層プロセスの新しいトレンド エアロゾルデポジション法による常温衝撃固化現象とその応用