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Coating Microstructure (coating + microstructure)

Distribution by Scientific Domains
Polymers and Materials Science50%

Selected Abstracts

Painting and Printing Living Bacteria: Engineering Nanoporous Biocatalytic Coatings to Preserve Microbial Viability and Intensify Reactivity

BIOTECHNOLOGY PROGRESS, Issue 1 2007
Michael C. Flickinger
Latex biocatalytic coatings containing ,50% by volume of microorganisms stabilize, concentrate and preserve cell viability on surfaces at ambient temperature. Coatings can be formed on a variety of surfaces, delaminated to generate stand-alone membranes or formulated as reactive inks for piezoelectric deposition of viable microbes. As the latex emulsion dries, cell preservation by partial desiccation occurs simultaneously with the formation of pores and adhesion to the substrate. The result is living cells permanently entrapped, surrounded by nanopores generated by partially coalesced polymer particles. Nanoporosity is essential for preserving microbial viability and coating reactivity. Cryo-SEM methods have been developed to visualize hydrated coating microstructure, confocal microscopy and dispersible coating methods have been developed to quantify the activity of the entrapped cells, and FTIR methods are being developed to determine the structure of vitrified biomolecules within and surrounding the cells in dry coatings. Coating microstructure, stability and reactivity are investigated using small patch or strip coatings where bacteria are concentrated 102 - to 103 -fold in 5,75 ,m thick layers with pores formed by carbohydrate porogens. The carbohydrate porogens also function as osmoprotectants and are postulated to preserve microbial viability by formation of glasses inside the microbes during coat drying; however, the molecular mechanism of cell preservation by latex coatings is not known. Emerging applications include coatings for multistep oxidations, photoreactive coatings, stabilization of hyperthermophiles, environmental biosensors, microbial fuel cells, as reaction zones in microfluidic devices, or as very high intensity (>100 g·L -1 coating volume·h -1) industrial or environmental biocatalysts. We anticipate expanded use of nanoporous adhesive coatings for prokaryotic and eukaryotic cell preservation at ambient temperature and the design of highly reactive "living" paints and inks. [source]

High Velocity Oxy Fuel Spraying of Cold Work Tool Steels- A Novel Approach to Thick Coatings for Wear Protection Applications,

ADVANCED ENGINEERING MATERIALS, Issue 12 2009
Arne Röttger
Abstract Within this work, HVOF sprayed coatings based on X220CrVMo13-4 cold work steel were applied to a S235JR construction steel substrate. The investigations focus on the influence of particle size and spray parameters on the coating microstructure, analyzed by means of optical microscope (OM) and scanning electron microscopy (SEM). Additional XRD measurements and micro hardness plots across the interface between substrate material and coating were carried out. Furthermore, the influence of particle size on the detected phases and coating porosity was studied. The results were compared with an X220CrMoV13-4 reference sample produced by HIP. [source]

The contribution of coating microstructure to degradation and particle release in hydroxyapatite coated prostheses

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2002
K. A. Gross
Abstract Plasma-sprayed coatings of hydroxyapatite powder are widely used on hip replacements. Commercially, they are supplied by a large number of companies and thus offer different coating design philosophies. This study focuses on a retrieved prosthetic stem that exhibited coating loss on the femoral stem occurring concurrently with third-body wear. The purpose of the research was to establish possible links between the coating microstructure and the clinical findings. A coated stem and cup were sectioned and the cross section was prepared to reveal the coating microstructure. Characterization included X-ray diffraction, FTIR spectroscopy, and crystalline particle quantification within the coating. It was found that the coating has a high amorphous content that provides fast resorption. The amount of crystalline particles increased on the distal location of the stem, the threads of the acetabular shell, and was generally higher on the cup. Accelerated degradation illustrated how the coating may be a particle-generating source by preferential dissolution of the amorphous phase, possibly allowing liberation of crystalline areas and other particulates at the substrate-coating interface. Such particles mainly include the less soluble hydroxyapatide formed from unmelted particles in the plasma or recrystallisation in the coating, but may also include entrapped grit lodged in the substrate during the roughening process. This study accents the importance of coating microstructure in understanding coating resorption. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 106,114, 2002; DOI 10.1002/jbm.10090 [source]

Painting and Printing Living Bacteria: Engineering Nanoporous Biocatalytic Coatings to Preserve Microbial Viability and Intensify Reactivity

BIOTECHNOLOGY PROGRESS, Issue 1 2007
Michael C. Flickinger
Latex biocatalytic coatings containing ,50% by volume of microorganisms stabilize, concentrate and preserve cell viability on surfaces at ambient temperature. Coatings can be formed on a variety of surfaces, delaminated to generate stand-alone membranes or formulated as reactive inks for piezoelectric deposition of viable microbes. As the latex emulsion dries, cell preservation by partial desiccation occurs simultaneously with the formation of pores and adhesion to the substrate. The result is living cells permanently entrapped, surrounded by nanopores generated by partially coalesced polymer particles. Nanoporosity is essential for preserving microbial viability and coating reactivity. Cryo-SEM methods have been developed to visualize hydrated coating microstructure, confocal microscopy and dispersible coating methods have been developed to quantify the activity of the entrapped cells, and FTIR methods are being developed to determine the structure of vitrified biomolecules within and surrounding the cells in dry coatings. Coating microstructure, stability and reactivity are investigated using small patch or strip coatings where bacteria are concentrated 102 - to 103 -fold in 5,75 ,m thick layers with pores formed by carbohydrate porogens. The carbohydrate porogens also function as osmoprotectants and are postulated to preserve microbial viability by formation of glasses inside the microbes during coat drying; however, the molecular mechanism of cell preservation by latex coatings is not known. Emerging applications include coatings for multistep oxidations, photoreactive coatings, stabilization of hyperthermophiles, environmental biosensors, microbial fuel cells, as reaction zones in microfluidic devices, or as very high intensity (>100 g·L -1 coating volume·h -1) industrial or environmental biocatalysts. We anticipate expanded use of nanoporous adhesive coatings for prokaryotic and eukaryotic cell preservation at ambient temperature and the design of highly reactive "living" paints and inks. [source]