NOPR Collection:

Composite building materials from natural fibers/ agro-forest residues

2020-04-01T00:00:00Z

Title: Composite building materials from natural fibers/ agro-forest residues Authors: Singh, Richa; Singh, Brajeshwar; Gupta, Manorama; Tarannum, Hina Abstract: Interest in using renewable resources such as natural fibers and agro-forest residues as reinforcements/fillers in polymer matrices has grown considerably for making wood alternatives in view of their low cost, easy availability, saving in energy and pollution free-production. In this paper, an overview on the global perspective of natural fiber reinforced composites has been outlined with reference to their applications in buildings. Researches carried out on polymer composites based on natural fibers and agro-forest residues are briefly reviewed in terms of their physico-mechanical properties and performance characteristics. During fabrication, 30-50 wt % sisal/jute fibers in laminates/sheets, 50-60 wt % rice husk in extruded/injection moldings and ~95 wt % pine needles in boards have been used. The sandwich composites used in the doors ( jute laminate face, and polyester-urethane foam core) have a density of 500-610 kg/m³and exhibited ~1.5% weight loss when exposed to termites according to ASTM D 3345. Based on the results, sisal/jute composite panels/ door shutters, shuttering plates, rice husk/plastic profile frames and pine needle composite boards have been successfully manufactured at pilot plant scale. Techno-economics and sustainability issues related to these composites have also been discussed in order to develop confidence among users and entrepreneurs. A comparative assessment between the properties of these newly developed products and commercial specification gives a clear guideline for users about their suitability in large scale adaptation in practice. Page(s): 137-149

Tribological investigation of HVOF-spray Cr3C2-25NiCr and WC-10Co-4Cr coated turbine steel under varied slurry erosion conditions

2020-04-01T00:00:00Z

Title: Tribological investigation of HVOF-spray Cr3C2-25NiCr and WC-10Co-4Cr coated turbine steel under varied slurry erosion conditions Authors: Sharma, Mithlesh; Goyal, Deepak Kumar; Kaushal, Gagandeep Abstract: In this work, high velocity oxy fuel (HVOF) method based spray coatings namely Cr₃C₂-25NiCr and WC-10Co-4Cr have been deposited on AISI304 turbine steels. An attempt has been made to analyze the coatings under accelerated slurry erosion conditions by employing a laboratory-developed slurry erosion testing set-up. The testing has been performed under varied conditions of slurry concentration, impact velocity and impact angle using the Taguchi approach. The microstructure of coating powder, erodent particles and deposited coatings have been studied using a scanning electron microscope (SEM) analysis. Erosion tests indicated that HVOF-spray Cr₃C₂-25NiCr and WC-10Co-4Cr coatings have been deposited on AISI304 steel exhibited significant improvements in the erosion resistance of AISI304 steel. The possible reason for such behaviour could be higher microhardness of HVOF-spray coatings in comparison with AISI304 bare steel. From SEM images of the samples taken prior and post slurry erosion tests, it has been observed that Cr₃C₂-25NiCr coating exhibited mixed (ductile and brittle) behaviour, though the WC-10Co-4Cr coating mostly demonstrated ductile behavior under conditions for erosion from the slurry. Apart from that, an attempt has been made to develop a functional equation based on the regression approach which could be employed to assess the erosion wear rate under a set of conditions. The predicted erosion wear results under varied conditions are in close relationship to experimental values. Page(s): 150-167

On the axial bearing capability of construction steel tube considering the uniform corrosion effect

2020-04-01T00:00:00Z

Title: On the axial bearing capability of construction steel tube considering the uniform corrosion effect Authors: Wang, Huajie; Zhang, Zhiwei; Qian, Hongliang; Song, Gang; Wang, Jiangbo; Fan, Feng Abstract: To study the law of corrosion on the mechanical properties of the components used in spatial steel structures and obtain the load-carrying capability of circular steel tubes under varying degrees of corrosion, experiments on a periodic spray have been designed to study the accelerated corrosion and axial loading of tubes without a protective layer. The experiment results show that the yield and ultimate load-carrying capacities of the components are heavily influenced by the corrosion, the latter being more sensitive to corrosion, and that a good functional relationship exists between the weight loss ratio and the load-carrying capability of the corrosive components. In addition, a finite element model of a circular steel tube experiencing corrosion has been established using ANSYS with an equivalent cross-section reduction method to simulate of the experiment results. The simulation results agree well with the experiment results, which effectively indicates that the corrosion of the steel tube components obeys the uniform corrosion law. And the equivalent cross-section reduction method also possesses good reliability. The results of the study provide a technical reference for research on the mechanical properties of larger building components such as circular steel tubes experiencing corrosion. Page(s): 168-178

Additive manufacturing of composite materials by FDM technology: A review

2020-04-01T00:00:00Z

Title: Additive manufacturing of composite materials by FDM technology: A review Authors: Mazurchevici, Andrei Danut; Nedelcu, Dumitru; Popa, Ramona Abstract: The additive manufacturing known also as “3D printing” or “rapid prototyping” is a present manufacturing method (compared to classic manufacturing methods) where layers of material are deposited at a time (successively) until a finished product is obtained. Depending on the phenomenon, material (in solid, liquid or powder state) used by the 3D printing equipment, a solid part, can be achieved using processes as: binder jetting,extrusion, material jetting, direct energy, vat photo-polymerization and powder bed fusion. In the present paper, we have summarized some knowledge regarding the 3D printing technologies, fused deposition modeling (FDM) prototyping method, and different types of test regarding PLA material properties (tensile test, flexural test). The FDM technology has registered benefits as cost, product quality, functionality and manufacturing time, continuously optimized and adopted by more and more companies, research institutes and consumers. Page(s): 179-192