scholarly journals Photochromic Organic-Inorganic Hybrid Nanocomposite Hard Coatings With Tailored Fast Switching Properties

1999 ◽  
Vol 576 ◽  
Author(s):  
M. Mennig ◽  
K. Fries ◽  
H. Schmidt
Keyword(s):  
Hard Coatings ◽  
Matrix Composition ◽  
Coating System ◽  
Fast Switching ◽  
Switching Times ◽  
Aromatic Character ◽  
Glass Slides ◽  
The Matrix ◽  
Cross Linker ◽  
Surface Modified

ABSTRACTA recently developed photochromic organic-inorganic nanocomposite (Nanomer®) coating system is investigated, which is based on an epoxysilane as network former, different bisepoxides as spacer and an organic amine as thermal cross-linker. This coating system is compatible with different photochromic dyes like oxazines, pyrans and fulgides and also with surface modified ceramic nanoparticles as filler in order to obtain macroscopic “hard properties” without changing the photochromic kinetics. In order to investigate the dye-spacer interactions and influence on the switching kinetic behavior, the matrix composition was diminished to the network former, the thermal cross-linker and two types (polar and nonpolar) of spacers in different concentrations. Four commercially available spirooxazines with different molecular sizes and polarities were incorporated into the matrices and coatings on glass slides were prepared by float-coating and cured at 130 °C for 2 h. The half darkening and half fading times of the coatings were measured by a fast diode array spectrometer as a function of spacer type and concentration for the four different dyes. The “nonpolar” spacer CHMG did not influence the switching kinetic of the dyes significantly and fast switching times of 2 s - 4 s were obtained. The “polar” spacer PCF (aromatic character) showed interactions with the dye molecules, which led to an increase in the switching times of up to 25 s. The retardation of the switching process increased with increasing spacer content and with increasing polar character of the dye molecule. From these results, it could be concluded that the photochromic behavior of the spirooxazines could be adjusted to different applications by interactions with polar spacers.

scholarly journals Nanocomposites Materials of PLA Reinforced with Nanoclays Using a Masterbatch Technology: A Study of the Mechanical Performance and Its Sustainability

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2133
Author(s):  
Helena Oliver-Ortega ◽  
Josep Tresserras ◽  
Fernando Julian ◽  
Manel Alcalà ◽  
Alba Bala ◽  
...  
Keyword(s):  
Food Packaging ◽  
Mechanical Performance ◽  
Polymeric Materials ◽  
Barrier Properties ◽  
Food Tray ◽  
Environmental Concerns ◽  
Poly Lactic Acid ◽  
The Matrix ◽  
Surface Modified ◽  
Being Moved

Packaging consumes around 40% of the total plastic production. One of the most important fields with high requirements is food packaging. Food packaging products have been commonly produced with petrol polymers, but due to environmental concerns, the market is being moved to biopolymers. Poly (lactic acid) (PLA) is the most promising biopolymer, as it is bio-based and biodegradable, and it is well established in the market. Nonetheless, its barrier properties need to be enhanced to be competitive with other polymers such as polyethylene terephthalate (PET). Nanoclays improve the barrier properties of polymeric materials if correct dispersion and exfoliation are obtained. Thus, it marks a milestone to obtain an appropriate dispersion. A predispersed methodology is proposed as a compounding process to improve the dispersion of these composites instead of common melt procedures. Afterwards, the effect of the polarity of the matrix was analyzing using polar and surface modified nanoclays with contents ranging from 2 to 8% w/w. The results showed the suitability of the predispersed and concentrated compound, technically named masterbatch, to obtain intercalated structures and the higher dispersion of polar nanoclays. Finally, the mechanical performance and sustainability of the prepared materials were simulated in a food tray, showing the best assessment of these materials and their lower fingerprint.

Precipitation of highly luminescent phases from PECVD Si suboxides

2004 ◽  
Vol 832 ◽  
Author(s):  
M. Perálvarez ◽  
M. López ◽  
B. Garrido ◽  
J.R. Morante ◽  
J. Barreto ◽  
...  
Keyword(s):  
Refractive Index ◽  
Phase Separation ◽  
Ion Implantation ◽  
Composition Profile ◽  
Matrix Composition ◽  
Light Sources ◽  
The Matrix ◽  
Detailed Composition ◽  
Preparation Route

ABSTRACTSi nanoclusters (Si-nc) embedded in SiO2 present outstanding luminescent emission in the visible and are the material of choice for the realization of efficient light sources integrated with Si technology. PECVD is an attractive preparation route but there is still the need to understand how Si excess and matrix composition affect the precipitation of Si-nc and their photoluminescence (PL) efficiency. The SiOx PECVD layers studied here have a Si excess up to 50% and a thickness between 50 and 100 nm. The phase separation, precipitation and growth of the Si-nc have been achieved by annealing at 1250 °C. For reference, the same study has been performed in Si-nc/SiO2 materials synthesized by ion implantation and annealing. Refractive index and thickness measured by ellipsometry show a densification of the layers after the H release during annealing. A detailed composition profile has been determined by XPS and FTIR analyses and shows almost complete phase separation except for the interfaces, where a depletion of Si-nc is found. EFTEM demonstrates that isolated Si-nc are formed for Si excess up to 25% while for higher Si excess a continuous Si phase is observed. The PL efficiency in PECVD samples is maximized for a Si excess of 17% which is the same Si excess than that for the most emitting implanted samples. No dependence of PL efficiency has been found on the presence of Nitrogen in the matrix (up to the 10%).

Design Method for Fast Switching Seat Valves for Digital Displacement® Machines

2014 ◽  
Author(s):  
Daniel B. Roemer ◽  
Per Johansen ◽  
Henrik C. Pedersen ◽  
Torben O. Andersen
Keyword(s):  
Pressure Loss ◽  
Design Method ◽  
Thermal Dissipation ◽  
Valve Design ◽  
Stroke Length ◽  
Efficient Operation ◽  
Fast Switching ◽  
Switching Times ◽  
High Bandwidth ◽  
Electro Magnetic

Digital Displacement® (DD) machines are upcoming technology where the displacement of each pressure chamber is controlled electronically by use of two fast switching seat valves. The effective displacement and operation type (pumping/motoring) may be controlled by manipulating the seat valves corresponding to the piston movement, which has been shown to facilitate superior part load efficiency combined with high bandwidth compared to traditional displacement machines. However, DD machines need fast switching on-off valves with low pressure loss for efficient operation, especially in fast rotating operation, where switching times must be performed within a few milliseconds. These valve requirements make a simulation based design approach essential, where mechanical strength, thermal dissipation, fluid dynamics and electro-magnetic dynamics must be taken into account. In this paper a complete design method for DD seat valves are presented, taking into account the significant aspects related to obtaining efficient DD valves with basis in a given DD machine specifications. The seat area is minimized and the stroke length is minimized to obtain fast switching times while considering the pressure loss of the valves. A coupled optimization is finally conducted to optimize the electro-magnetic actuator, leading to a valve design based on the chosen valve topology. The design method is applied to an example DD machine and the resulting valve design fulfilling the requirements is presented.

Slurry Wear Test of Long Kenaf Polyester Composite (LKPC) and Long Kenaf Polyester with Fiberglass Composite

2013 ◽  
Vol 393 ◽  
pp. 919-924
Author(s):  
Muhd Azimin Ab Ghani ◽  
A.F. Ahmad Kamal ◽  
Mohamad Ali Ahmad ◽  
Y.M.D. Taib ◽  
Z. Salleh ◽  
...  
Keyword(s):  
Sea Water ◽  
Wear Test ◽  
Matrix Composition ◽  
Slurry Erosion ◽  
Composite Surface ◽  
Wear And Friction ◽  
Fiberglass Composite ◽  
The Matrix ◽  
Polyester Composite ◽  
Erosion Test

This paper presents an experimental study on the influence of fiberglass woven in Long Kenaf Polyester Composite (LKPC). Wear and friction characteristics were examined using sea water and sand as a slurry. Wear test were carried out using Slurry Erosion Test Rig (TR-40). These tests were performed at room temperature with speed of 200 rpm for every 2 km interval. The results from the tests show that mass loss were depends on the matrix composition of the composite. Surface Roughness, Ra, was consistently reduced after each test in all cases.

Influence of WC Particle Size and Matrix Composition on the Behavior of WC-Co-Cr Coatings Sprayed by the HVOF Process

1997 ◽  
Author(s):  
J. Berget ◽  
E. Bardal ◽  
T. Rogne
Keyword(s):  
Particle Size ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
Chromium Content ◽  
Deposition Efficiency ◽  
Matrix Composition ◽  
Coating Properties ◽  
Hvof Process ◽  
Erosion Corrosion ◽  
The Matrix

Abstract WC-Co-Cr powders with different WC particle size have been sprayed by the HVOF process. At constant spraying conditions the powders give coatings of different quality. The deposition efficiency during spraying of powders containing large WC particles was found to be low compared to powders with finer WC grains. In addition the amounts of porosity and cracks were different. The coatings have been characterised by different methods. Erosion and erosion-corrosion tests showed that the WC particle size also influence the wear resistance of the coatings. Small WC particle size was found to be beneficial. Chemical composition of the matrix was also found to be decisive for the coating properties. An increase of the chromium content improved the erosion-corrosion resistance.

PVD Coated Tools and Surface-Structured Workpieces in Dry Cold Forming of Steel

2020 ◽  
Vol 404 ◽  
pp. 19-27
Author(s):  
Kirsten Bobzin ◽  
Tobias Brögelmann ◽  
Nathan Christopher Kruppe ◽  
Thomas Bergs ◽  
Patrick Mattfeld ◽  
...  
Keyword(s):  
Physical Vapor Deposition ◽  
Field Trials ◽  
Hard Coatings ◽  
Friction Reduction ◽  
Industrial Scale ◽  
Coating System ◽  
Punch Force ◽  
Cold Forming ◽  
Die Geometry ◽  
Tool Coating

Cold forming, particularly forward impact extrusion, is used for mass production of steel components. To ensure robust forming processes, the workpieces are usually phosphated and then soaped as well as mineral oil-based lubricants are used. As these lubricants are often harmful to the environment and health, alternative approaches are to be investigated from an ecological, economic and legislative perspective. To achieve dry, lubricant-free cold forming of steel, two approaches are being pursued here. The tool-sided approach focuses on self-lubricating hard coatings, which are deposited on the forming tools by means of physical vapor deposition (PVD). The developed coating system CrAlN+Mo:S is synthesized in an industrial coating unit by a hybrid sputtering process, which combines direct current (DC) and high power pulsed magnetron sputtering (HPPMS) technology. The coating consists of a hard matrix CrAlN which is modified by Mo and S to provide friction reduction due to the in situ formation of MoS2 reaction layers under tribological load. The workpiece-sided approach focuses on the surface structuring by shot peening with various peening materials and particle shapes. In order to evaluate the influence of the self-lubricating tool coating CrAlN+Mo:S and the various workpiece topographies, dry full forward impact extrusion tests were carried out in an industrial scale with coated and uncoated tools. On the one hand, a one-shouldered die geometry and on the other hand a two-shouldered die geometry were tested. The field trials reveal that for both die geometries, the tool coating significantly reduces the punch force and the wear compared to the uncoated dies. Depending on the workpiece topography, it was shown that a smoother surface leads to reduced adhesive wear. Furthermore, it was proven that the dies with an opening diameter of D = 31.4 mm and an outlet diameter of d = 20.7 mm could be coated continuously over a length of l = 50 mm on the entire inner surface. After the dry field trials, the CrAlN+Mo:S coating remained completely intact. Hence, the developed coating system CrAlN+Mo:S exhibits great potential to conduct dry, lubricant-free cold forming of steel at industrial scale.

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