Tarnishing film-induced brittle cracking of brass

2009 ◽  
Vol 24 (7) ◽  
pp. 2409-2415 ◽  
Author(s):  
Cheng Zhang ◽  
Yan Jing Su ◽  
Li Jie Qiao ◽  
Wu Yang Chu
Keyword(s):  
Room Temperature ◽  
Film Rupture ◽  
Galvanic Current ◽  
Ductile Mode ◽  
Brass Surface ◽  
Strain Rate Loading ◽  
Periodic Current ◽  
Brass Sample ◽  
Initial Cracks ◽  
Deposited Film

Tarnishing film was developed on the brass surface in Mattsson's solution at room temperature. The filmed brass was removed from the solution, dried, and subjected to a slow strain rate (loading speed = 0.5 mm/min) in air for studying the effect of the film on crack propagation in the brass substrate. It was observed that initial cracks started to emerge in the film and then propagated to the brass matrix in a brittle intergranular manner. However, it changed into a ductile mode after removing the deposited film. The galvanic current between platinum wire and filmed brass sample in Mattson's solution was investigated. The results showed that periodic current fluctuations were observed when the sample was under a constant applied load. These observations showed that the film rupture-formation occurred at cracks under the stress-corrosion cracking condition.

Electrical Performances of Low Temperature Annealed Hafnium Oxide Deposited at Room Temperature

2006 ◽  
Vol 514-516 ◽  
pp. 58-62 ◽  
Author(s):  
Luís Pereira ◽  
Pedro Barquinha ◽  
Elvira Fortunato ◽  
Rodrigo Martins
Keyword(s):  
Dielectric Constant ◽  
Charge Density ◽  
Hafnium Oxide ◽  
Room Temperature ◽  
Flat Band ◽  
Interface Properties ◽  
Flat Band Voltage ◽  
Fixed Charge Density ◽  
Gas Atmosphere ◽  
Deposited Film

In this work, HfO2 was deposited by r.f. sputtering at room temperature and then annealed for different times at 200°C in a forming gas atmosphere. After annealing for 2 hours the HfO2 layers present a reduction on the flat band voltage of about 1 V, relatively to the as deposited film, decreasing from -2.23V down to -1.28 V. This means an improvement of the interface properties and a reduction on the oxide charge density from 1.33×1012 cm-2 to 7.62×1011 cm-2. The dielectric constant reaches a maximum of 18.3 after 5h annealing due to film’s densification. When annealing for longer times such as 10h a small degradation of the electrical properties is observed. After 10h annealing the dielectric constant, flat band voltage and fixed charge density are respectively, 14.9, -2.96 V and 1.64 ×1012 cm-2 and the leakage current also increases due to film’s crystallization.

Room Temperature Photoluminescence Spectra of Annealed PECVD Silicon Nitride Thin Films

1992 ◽  
Vol 284 ◽  
Author(s):  
C. Savall ◽  
E. Bustarret ◽  
J. P. Stoquert ◽  
J. C. Bruyére
Keyword(s):  
Silicon Nitride ◽  
Room Temperature ◽  
Visible Region ◽  
Broad Emission Band ◽  
Isochronous Annealing ◽  
Room Temperature Photoluminescence ◽  
Pl Spectra ◽  
Energy Part ◽  
Pl Spectrum ◽  
Deposited Film

ABSTRACTWe present the changes upon isochronous annealing in the room temperature photoluminescence (PL) spectra of nearly stoichiometric silicon nitride. Samples are prepared by the 50kHz PECVD of a N2/SiH4/Helium gas mixture at 350°C. In the as-deposited films the hydrogen content was around 11% for a refractive index of 1.98. For a photoexcitation at 351 nm, the polarized PL spectrum of the as-deposited film is characterized by a main broad emission band in the visible region with a maximum at 2.55eV. A second narrow peak (FWHM = 55meV), at 3.02eV is observed. We study the evolution of the PL spectra with different isochronous anneals from 350°C to 1000°C. Even though the general shape of the PL spectra does not change, we observe an increase of quantum efficiency with maximum value upon 750°C annealing. Beyond this temperature the low energy part of the PL spectrum shows a slight increase. These variations are compared to those of the infrared absorption peaks measured on the same samples. Both the temperature dependence of the intensity of a well defined absorption peak in the Si-H stretching mode region and that of the PL features can be explained assuming that solid state chemical reactions involving hydrogen and Si-Si bonds occur in the bulk of the alloy.

scholarly journals Low Deposition Temperature-Induced Changes of the Microstructure and Tribological Property of WS2 Film

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 227 ◽  
Author(s):  
Ming Hu ◽  
Yi Dong ◽  
Yan Wang ◽  
Desheng Wang ◽  
Dong Jiang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Substrate Temperature ◽  
Tribological Properties ◽  
Room Temperature ◽  
Compact Structure ◽  
Radio Frequency Sputtering ◽  
Initial Substrate ◽  
Wear Life ◽  
Induced Changes ◽  
Deposited Film

Pure WS2 films were prepared by the radio frequency sputtering of a WS2 target with the initial substrate temperature controlled to −40, −25, 0 °C and room temperature by cooling the holder with liquid nitrogen, respectively. The influence of the substrate temperature on the microstructures and the tribological properties of the prepared films have been evaluated and the wear mechanism of the films was explained. It revealed that with decreasing the substrate temperature, the prepared WS2 film changed from the loose and coarse columnar plate structure for film deposited at room temperature to a much more compact morphology for film deposited at −40 °C. The WS2 film deposited at low temperature of −40 or −25 °C exhibited a long wear life higher than 5.0 × 105 sliding cycles, while this was about 1.5 × 105 cycles for the WS2 deposited at room temperature. The improved tribological properties for the low temperature-deposited film were mainly attributed to the much lower wear rate resulted from the compact structure as well as the sustained and steadily formed transform layer on the counterpart ball.

Low Temperature Chemical Synthesis of p-Type SnS Thin Films Suitable for Photovoltaic Structures

2013 ◽  
Vol 209 ◽  
pp. 82-85
Author(s):  
T.H. Patel
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Band Gap ◽  
Room Temperature ◽  
Chemical Compositions ◽  
X Rays ◽  
Average Grain Size ◽  
Sns Thin Films ◽  
P Type ◽  
Deposited Film

SnS thin film has been deposited on glass substrate at room temperature using low cost, environmental friendly chemical bath deposition (CBD) technique. The structural parameters of the deposited film have been investigated through X- ray diffraction measurements. The deposited SnS film found almost crystalline with preferred orientations along (111) planes revealing an orthorhombic phase of herzenbergite SnS structure. The lattice parameters and dislocation density were determined. The average grain size estimated to be ~ 25 nm. The surface morphology of the film examined using scanning electron microscopy (SEM) show uniform granular and any crack or pinhole free deposition of the film. The chemical compositions of the film examined using energy dispersive analysis of x-rays (EDAX) confirmed stoichiometric deposition. The analysis of the optical absorption spectra of the deposited film in the wavelength range of 200-1200 nm indicate that direct allowed transitions are dominant in the film. The direct band gap of the film determined to be ~ 1.92 eV which is higher than those reported earlier for bulk or single crystal SnS, exhibiting quantum size effect at the observed grain size in the film. This value of band gap is promising for possible use of the deposited film as absorption layer in photovoltaic structures like solar cells. The thermoelectric power measurements indicate p-type electrical conductivity of the deposited films. A systematic study on room temperature chemical deposition and characterization of SnS thin films suitable for absorber layer in photovoltaic structures has been reported.

Structure–property correlation of nanostructured WO3 thin films produced by electrodeposition

2004 ◽  
Vol 19 (9) ◽  
pp. 2576-2585 ◽  
Author(s):  
M. Deepa ◽  
A.K. Srivastava ◽  
S. Singh ◽  
S.A. Agnihotry
Keyword(s):  
Optical Switching ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Lithium Ion ◽  
Structure Property ◽  
Transmission Electron ◽  
Peroxotungstic Acid ◽  
Order Of Magnitude ◽  
A Charge ◽  
Deposited Film

Nanocrystalline tungsten oxide (WO3) films were electrodeposited potentiostatically at room temperature on transparent conducting substrates from an ethanolic solution of acetylated peroxotungstic acid prepared from a wet chemistry process. The changes that occur in the microstructure and the grain size of the as-deposited WO3 films as a function of annealing temperature are simultaneously accompanied by a continually varying electrochromic performance. X-ray diffraction studies revealed the transformation of a nanocrystalline as-deposited WO3 film into a highly crystalline triclinic WO3 as the annealing temperature was raised from room temperature to 500 °C. The microstructural evolution with the increasing annealing temperature of the as-deposited film was further exemplified by transmission electron microscopy (TEM) studies. While the as-deposited film was composed of uniformly distributed ultra fine nanograins, the most noticeable feature seen in these films annealed at 250 °C was the presence of open channels which are believed to promote lithium ion motion. Films annealed at 400 °C exhibited coarse grains with prominent grain boundaries that hinder lithium ion movement, which in turn reduces the film’s ion insertion capacity. In concordance with the TEM results, the 250 °C film had the highest ion storage capacity as it exhibited a charge density of 67.4 mC cm−2 μm−1. The effect of microstructure was also reflected in the high transmission modulation (64%) and coloration efficiency (118 cm2 C−1) of the 250 °C film at 632.8 nm. Contrary to the superior electrochromic performance of the 250 °C film, the optical switching speeds between the colored and bleached states of the as-deposited WO3 film declined considerably as a function of annealing temperature. Also, the diffusion coefficient for lithium ions was greater by at least an order of magnitude for the as-deposited film as compared to the 250 and 500 °C films. In this report, the influence of microstructural changes that are brought about by the annealing of the as-deposited WO3 films on their coloration-bleaching dynamics is evaluated in terms of their structural, electrochromic, and electrochemical properties.

InSe Nanothin Film with Ar-Gas Low Vacuum Pressure

2014 ◽  
Vol 606 ◽  
pp. 15-18
Author(s):  
Falah I. Mustafa ◽  
Mooroj Ali
Keyword(s):  
Thin Films ◽  
Diffraction Analysis ◽  
Room Temperature ◽  
Energy Gap ◽  
X Ray Diffraction ◽  
Argon Gas ◽  
X Ray ◽  
Glass Substrates ◽  
Deposited Film ◽  
Deposited Films

InxSe1-x(x = 0.4, 0.5, 0.6) thin films are deposited at room temperature on glass substrates with thickness ~500nm by thermal evaporation technique. The X-Ray diffraction analysis showed that both the as-deposited films In2Se3and InSe (x= 0.4 and 0.5) are amorphous in nature while the as-deposited film In3Se2is polycrystalline and the values of energy gap are Eg=1.44eV for In2Se3, Eg=1.16eV for InSe and Eg=0.78eV for In3Se2. The same technique used with insert Argon gas at pressure 0.1 mbar where InxSe1-x(x = 0.4, 0.5, 0.6) thin films are deposited at room temperature on glass substrates with thickness ~100nm. The X-Ray diffraction analysis showed that the as-deposited films In2Se3are amorphous in nature while the as-deposited film InSe and In3Se2are Nanocrystalline with grain size 33nm and 55nm respectively and the values of energy gap are Eg=1.55eV for InSe and Eg=1.28eV for In3Se2. The energy gap of InSe thin films increase with Argon gas assist and phases changes from amorphous and polycrystalline to nanostructure material by thermal vacuum deposition technique.

Study of Solder/Copper Interface Behavior Under Varying Strain Rates

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Y. W. Kwon ◽  
A. M. Luteran ◽  
J. M. Didoszak ◽  
A. S. Kwon
Keyword(s):  
Strain Rate ◽  
Room Temperature ◽  
Fracture Strain ◽  
Peak Stress ◽  
Absolute Error ◽  
Material Behavior ◽  
Interface Fracture ◽  
Strain Rates ◽  
Test Results ◽  
Strain Rate Loading

This paper investigates the mechanical behavior of a copper–solder interface when subjected to varying strain rate loading between 0.05 s−1 and 10.0 s−1. The copper is alloy 101, and the solder is lead-free type with a composition of 96% tin and 4% silver. Both uniform and nonuniform two-level strain rate loadings were applied. For the two-level strain rate loading, the strain rate was changed from one level to another during the loading process as a step change. The strain rate tests were performed at room temperature as well as at an elevated temperature of 65 °C. The test results showed significant effects of uniform and nonuniform strain rates as well as temperature on fracture surface, peak stress, fracture strain, modulus, and stored energy density until fracture. Generally, a higher strain rate increased the peak stress and fracture strain, but decreased the modulus. The heated specimens showed significantly reduced strength and fracture strain at high strain rates when compared to the specimens tested at room temperature. For the two-level strain rates, the sequence of the loading rates affected the material behavior significantly. The peak stress under the two-level strain rates might be located outside the range that was determined by the two individual uniform strain rates occurring in the two-level rates. On the other hand, the fracture strain under two-level strain rate loading always fell inside that range. An expression was proposed to predict the interface fracture strains for the case of a two-level strain rate loading based on the data of each respective single-level strain test. The prediction was reasonable when compared to the experimental data with an average absolute error of 10%.

scholarly journals Rapid Formation of Kinetically Sprayed Cu-Sn Intermetallic Film

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Dahyun Choi ◽  
Suhee Kang ◽  
Hyungsub Kim ◽  
Hyojun Kim ◽  
Caroline Sunyong Lee
Keyword(s):  
Thin Film ◽  
Room Temperature ◽  
Heat Energy ◽  
Mixed Powder ◽  
In Situ Deposition ◽  
Short Time ◽  
Deposited Film ◽  
Spraying Process ◽  
Spraying Method

The kinetically spraying method was used to fabricate an in situ copper- (Cu-) tin (Sn) intermetallic compound (IMC) film with its thickness of approximately 1 μm using a Cu-Sn mixed powder. Microsized Cu (~5 μm) and Sn (~10 μm) powders were mixed at its ratio of 45 : 55 wt.%, respectively, and then deposited onto a silicon substrate, forming an IMC layer. The actual composition of the deposited film was measured to be at a Cu : Sn ratio of 36 : 64 wt.% (in situ kinetically sprayed at 200°C). This kinetically sprayed process uses the energy source of collision and heat energy simultaneously, leading to the formation of an IMC phase. The IMC phase of Cu6Sn5 was formed successfully within 3 minutes of in situ deposition. Moreover, we obtained a Cu6Sn5 phase when the thin film was annealed in a furnace for 1 hour immediately after kinetically spraying at room temperature. However, an IMC phase was not formed in the thin film when kinetically sprayed at room temperature followed by heating on a hot plate for 3 minutes. It seems that the simultaneous supply of collision and heat energy is crucial to result in phase formation. Therefore, we have proven that the kinetically spraying process is capable of fabricating a super-thin layer of IMC film within a short time.

Spontaneous quasi-periodic current self-oscillations in a weakly coupled GaAs/(Al,Ga)As superlattice at room temperature

2013 ◽  
Vol 102 (24) ◽  
pp. 242107 ◽  
Author(s):  
Yuyang Huang ◽  
Wen Li ◽  
Wenquan Ma ◽  
Hua Qin ◽  
Holger T. Grahn ◽  
...  
Keyword(s):  
Room Temperature ◽  
Weakly Coupled ◽  
Periodic Current

Structural and Magnetic Properties of Off-Stochiometric Ni-Mn-Al Heusler Alloy Thin Film

2008 ◽  
Vol 136 ◽  
pp. 139-144
Author(s):  
Vijay Kumar Srivastava ◽  
Saurabh Srivastava ◽  
Ratnamala Chatterjee
Keyword(s):  
Magnetic Properties ◽  
Heusler Alloy ◽  
Room Temperature ◽  
Rf Magnetron Sputtering ◽  
Silicon Substrates ◽  
Alloy Thin Film ◽  
Vibrating Sample Magnetometer ◽  
Good Crystallinity ◽  
Deposited Film ◽  
Full Heusler

The initials results on growth and structural properties of Ni-Mn-Al full Heusler alloy thin films on silicon substrates deposited by RF magnetron sputtering is reported in this paper. Good crystallinity in the film is obtained by optimizing the sputtering parameters. The as-deposited film was post-annealed in vacuum in the temperature range between 150 °C, 250 °C and 450 °C for 60 min. It is observed that as deposited film shows nanocrystalline in nature. The film annealed at 450 °C shows L21 structure. The magnetic properties of the NiMnAl films at room temperature are measured by vibrating sample magnetometer [VSM]. It is found that the annealed samples shows clear saturating loop whereas the as prepared film is paramagnetic in nature.

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