Identification of Inhomogeneous Temperature on Stainless Steel using Statistical Analysis

Corrosion in stainless steel, abbreviated as SS, is still an exciting topic to study. Even though SS is a corrosion resistance material, this property will be degraded when exposed to high temperatures for a long time because of σ phase, such as a Fe-Cr compound, formation. The presence of this phase can be observed using a special chemical etchant solution that will give five specific colours to this phase: light brown, dark brown, bluish brown, light blue, and dark blue. In this study, the specimen sample is from ASTM A297. Furthermore, the metallography process is carried out to obtain microstructure images that describe the σ phase. Here, two grains were taken as objects to discretize with one of them was around the specimen sample center and the other was close to the boundary with the environment. The discretization resulted in a 2 x 5 frequency table, called contingency table, that is analysed by the independence χ2-test. The contingency table is also represented geometrically in cartesian. The study shows that two grains were not independent. The grain which was around the specimen sample center contained many σ phases dominated by light blue colour (43%). In other words, the prolonged heating did not give homogeneous corrosion level.

Novel Hybrid Conductor of Irregularly Patterned Graphene Mesh and Silver Nanowire Networks

We prepared the hybrid conductor of the Ag nanowire (NW) network and irregularly patterned graphene (GP) mesh with enhanced optical transmittance (~98.5%) and mechano-electric stability (ΔR/Ro: ~42.4% at 200,000 (200k) cycles) under 6.7% strain. Irregularly patterned GP meshes were prepared with a bottom-side etching method using chemical etchant (HNO3). The GP mesh pattern was judiciously and easily tuned by the regulation of treatment time (0–180 min) and concentration (0–20 M) of chemical etchants. As-formed hybrid conductor of Ag NW and GP mesh exhibit enhanced/controllable electrical-optical properties and mechano-electric stabilities; hybrid conductor exhibits enhanced optical transmittance (TT = 98.5%) and improved conductivity (ΔRs: 22%) compared with that of a conventional hybrid conductor at similar TT. It is also noteworthy that our hybrid conductor shows far superior mechano-electric stability (ΔR/Ro: ~42.4% at 200k cycles; TT: ~98.5%) to that of controls (Ag NW (ΔR/Ro: ~293% at 200k cycles), Ag NW-pristine GP hybrid (ΔR/Ro: ~121% at 200k cycles)) ascribed to our unique hybrid structure.

Effect of Etchant Concentration on the Optical Properties and Surface Topography of MoO3 Selective Solar Absorber Thin Films

ABSTRACTA novel technique providing a cost effective sustainable wet chemical etching method of synthesizing black Moly thin films rapidly has been presented. A top- down method for fabricating MoO3 has been investigated to understand the effect of chemical etchant concentration on the structural, morphological and optical properties of the thin films on Mo substrates. The XRD patterns demonstrated the formation of Tugarinovite MoO2 films on Mo substrate after annealing at 500°C in a vacuum. In this work, we developed nanostructured MoO3 on Mo substrate solar absorber, with a high solar absorptance of over 89%. These results suggest that solar absorbers made from refractory metal oxide nanostructures can be used for solar thermal applications.

The Effect of Machining Parameters on Weight Removal in Chemical Machining of Titanium Alloy

Chemical machining (CHM) processes are one of the non-conventional machining processes the material removal occurs when the machined part contact with a strong chemical etchant solution. This study aiming to study the influences of machining time, machining temperature and the concentration of the used etchant solution on the weight removal of chemically machined titanium alloy, in this study two different etchant concentration of mixture acids consist of hydrofluoric acid (HF) mixed with nitric acid (HNO3) in specific quantities are used, the first etchant concentration consist of (9 vol.% HF , 14 VOL.% HNO3 in 77 vol.% distilled water) the second concentration (12 vol.% HF, 16 vol.% HNO3 in 72 vol.% distilled water) to chemically machine eight specimens of (30 x 10 x 1) mm size by using four level of machining time (4, 6, 8 and 10) min and four level of machining temperature (35, 40, 45 and 50) for both concentrations as a machining conditions. The results show that the weight removal increased with the increasing of the time, temperature and the concentration of the used etchant

Chemical Infiltration through Deep UV Photoresist

Still nowadays in integrated circuits manufacturing, few materials patterns are defined by a wet etch on patterned deep UV photoresist. From dies to dies generation, an optical performance improvement is required, hence an evolution with thinner and thinner positive resist. This makes these latter more sensitive to wet chemical etchant through the polymer, reducing their protection of the underneath material. Following characterizations enable a clear understanding of BHF (Buffered HF) benefits versus diluted HF during a gate oxide definition.

Anti-Reflective Porous Silicon Features by Substrate Conformal Imprint Lithography for Silicon Photovoltaic Applications

Silicon photovoltaic cells require anti-reflection treatments in order to minimise optical losses and improve cell efficiencies. Commercially, the silicon surface is textured using a chemical etchant followed by the addition of an anti-reflective coating to further suppress reflectivity. We present a process using metal assisted etching to create porous silicon features capable of reducing reflectivity to less than 5%. A method for producing porous silicon using Substrate Conformal Imprint Lithography (SCIL) has been developed in order to pattern the nanoscale anti-reflective structures onto silicon wafers.

Etch Rate and Dimensional Accuracy of Machinable Glass Ceramics in Chemical Etching

Machinable glass ceramic (MGC) is well known in the micro-electromechanical system and semiconductor industry. Chemical etching is used in this experiment to study the performance of MGC. The etching rate of MGC and its accuracy by indentation method is studied. The categoric parameter applied here is the type of chemical etchant used: hydrochloric (HCl), hydrophosphoric (H3PO4) and hydrobromic (HBr) acids; and, numerical parameters are etching temperature and etching solution. The experimental investigation that was carried out is governed by design of experiment (DoE).