Development and design of binder systems for titanium metal injection molding: An overview

Titanium metal injection molding (Ti-MIM) has been practiced since the late 1980s. Logically, the Ti-MIM practice follows the similar processes developed for the antecedent materials such as stainless steel and ceramics. Although Ti-MIM is a favorite research topic today, the issue of convincing the designers to use Ti injection-molded parts still exists. This is mainly because of the concern about contamination which seems unavoidable during the Ti-MIM process. Much information about the binder formulation, powder requirements, debinding, and sintering is available in the literature. There are several powder vendors and feedstock suppliers. However, most of the binders in the feedstock are proprietarily protected. The disclosed information on the binders used for formulating powder feedstock is very limited, which in turn discourages their adoption by engineering designers. This overview intends to discuss some of major binder systems for Ti-MIM available in the literature. It serves to provide a guideline for the Ti-MIM practitioners to choose a suitable powder feedstock

GEOPOL®. The innovated environment friendly inorganic binder system

This paper deals with the complete technology of inorganic geopolymer binder system GEOPOL® which is a result of long term research and development. The objective of this paper is to provide a theoretical and practical overview of the GEOPOL® binder system and introduce possible ways of moulds and cores production in foundries. GEOPOL® is a unique inorganic binder system, which is needed and welcomed in terms of the environment, the work environment, and the sustainable resources. The GEOPOL® technology is currently used in the foundries for three basic production processes/technologies: (1) for self-hardening moulding mixtures, (2) sand mixtures hardened by gaseous carbon dioxide and (3) the hot box technology with hot air hardening. The GEOPOL® technology not only solves the binder system and the ways of hardening, but also deals with the entire foundry production process. Low emissions produced during mixing of sand, moulding, handling, and pouring bring a relatively significant improvement of work conditions in foundries (no VOCs). A high percentage of the reclaim sand can be used again for the preparation of the moulding mixture.Web of Science19111610

Processibility of black garbage bag as a novel binder system in metal injection molding

The issues to be highlighted here is to fundamentally evaluate the potential of using waste Garbage Bag from High Density Polyethylene (HDPE) as a backbone binder in Metal Injection Molding (MIM.) This is by the fact that the earth has tons of Garbage Bag disposed every day and researcher believes such waste can be converted into more beneficial industrial product. Thus this research investigates the potential uses of garbage bag as a novel binder system in metal injection molding. Stainless steel SS316L was used which is garbage bag (HDPE) and palm kernel acts as binder system. Feedstock with three composition 30%, 40% and 55% powder loading (PL) were injected by injection molding machine with several injection parameter were optimized such as injection temperature (A), barrel temperature (B), injection pressure (C) and Speed (D). The optimum parameter for highest green density, strength were optimized in Taguchi Method orthogonal Array L9 ( 3 ) and analysed by using Signal to Noise Ratio (S/N ratio).Results shows the optimum variables for 30% PL the highest density is A0, B2, C1 and D0 while for green strength are combination of A0, B0, C0, D1. For powder loading 40%, the optimize parameter for highest green part density are A2, B2, C0 and D2 and A0, B0, C1, and D0 for green strength. Besides, the highest green density for 0.55 PL by following the optimum variable are A2 , B2, C0 and D2 while for highest green strength are A2, B2, C2, and D2. Garbage bag are suitable acted as a binder system in metal injection molding. Furthermore, it could reduce the cost of binder system. The suitable volume ratios in mixing process produce a better feedstock in order to produce the green part by injection molding. Taguchi Method is among the best method in optimizing the injection variables as it can reduce the cost, time, improve accuracy and efficienc

Polyisoprene Captured Sulfur Nanocomposite Materials for High-Areal-Capacity Lithium Sulfur Battery

A polyisoprene-sulfur (PIPS) copolymer and nano sulfur composite material (90 wt % sulfur) is synthesized through inverse vulcanization of PIP polymer with micrometer-sized sulfur particles for high-areal-capacity lithium sulfur batteries. The polycrystalline structure and nanodomain nature of the copolymer are revealed through high-resolution transmission electron microscopy (HRTEM). PIP polymer is also used as binders for the electrode to further capture the dissovlved polysulfides. A high areal capacity of ca. 7.0 mAh/cm2 and stable cycling are achieved based on the PIPS nanosulfur composite with a PIP binder, crucial to commercialization of lithium sulfur batteries. The chemical confinement both at material and electrode level alleviates the diffusion of polysulfides and the shuttle effect. The sulfur electrodes, both fresh and cycled, are analyzed through scanning electron microscopy (SEM). This approach enables scalable material production and high sulfur utilization at the cell level

Analysis of rheological behaviour of titanium feedstocks formulated with a water-soluble binder system for powder injection moulding

Binder selection and formulation are critical in powder injection moulding. Binders play a key role in controlling the rheological properties of a feedstock and influence whether the resulting feedstock can be successfully injection moulded, debound and sintered without defects. A four-step process was used to mix hydride-dehydride titanium alloy (processed) powder (Ti-6Al-4 V) with a polyethylene glycol (PEG) based water soluble binder system. The rheological properties, including flow behaviour index, flow activation energy, fluidity and melt flow index of the homogeneous feedstock, were determined with a capillary rheometer. All feedstock formulations exhibited shear thinning flow behaviour. The optimum feedstock consisting of 60 vol.% powder content, 32 vol.% PEG, 6 vol.% polyvinyl butyryl and 2 vol.% stearic acid was suitable for titanium injection moulding

Diffusion-based DNA target colocalization by thermodynamic mechanisms

In eukaryotic cell nuclei, a variety of DNA interactions with nuclear elements occur, which, in combination with intra- and inter- chromosomal cross-talks, shape a functional 3D architecture. In some cases they are organized by active, i.e. actin/myosin, motors. More often, however, they have been related to passive diffusion mechanisms. Yet, the crucial questions on how DNA loci recognize their target and are reliably shuttled to their destination by Brownian diffusion are still open. Here, we complement the current experimental scenario by considering a physics model, in which the interaction between distant loci is mediated by diffusing bridging molecules. We show that, in such a system, the mechanism underlying target recognition and colocalization is a thermodynamic switch-like process (a phase transition) that only occurs if the concentration and affinity of binding molecules is above a threshold, or else stable contacts are not possible. We also briefly discuss the kinetics of this "passive-shuttling" process, as produced by random diffusion of DNA loci and their binders, and derive predictions based on the effects of genomic modifications and deletions