16,675 research outputs found
Wet granulation in laboratory scale high shear mixers: Effect of binder properties
No full textThe effect of binder properties on torque curves, granule growth kinetics, wet mass consistency and dry granule strength has been investigated in this study. Granulation runs have been performed on a fine cohesive microcrystalline cellulose powder (Avicel 105, d50 = 20 μm) in two types of laboratory high shear mixers: a Mi-Pro high shear mixer using a 1.9 L bowl and a 6 L Diosna high shear mixer. Binders used included ultra-pure water and solutions of varying concentrations of PVP and HPMC allowing us to cover different values for parameters like viscosity and work of adhesion. Torque curves recorded during granulation are found to allow good control of the process. Optimum liquid requirement for granulation has been found to vary with binder type and decrease with increasing viscosity while granule growth kinetics has been found to be to be related to the work of adhesion for low viscosity binders. Granule strength has been evaluated for wet granules by the means of wet mass consistency measurements on a mixer torque rheometer and for dried granules by means of uniaxial compression tests on a Texture Analyser mechanical testing machine. For low viscosity binders both wet mass consistency and dry granule strength have been found to depend on the work of adhesion. For high viscosity bindershigherwet mass consistencies but lower dry granule strengths have been observed. Granulating on the larger 6 L scale has shown that constant impeller tip speed offers good agreement in terms of mean granule size however granule size distribution seems to be scale dependan
Analysis of rheological behaviour of titanium feedstocks formulated with a water-soluble binder system for powder injection moulding
No full textBinder 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
Development and design of binder systems for titanium metal injection molding: An overview
No full textTitanium 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
Theophrast's Charaktere / Uebersetzt und erläutert von Wilhelm Binder
No full textTHEOPHRAST'S CHARAKTERE / UEBERSETZT UND ERLÄUTERT VON WILHELM BINDER
Theophrast's Charaktere / Uebersetzt und erläutert von Wilhelm Binder ([1])
Titelseite ([1])
Einleitung. ([3])
Vorrede. (13)
I. - XXX. (15)
Anmerkungen. (49
Preparation and Characterisation of Binder-Free All-Cellulose Composites
No full textThe copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the authorA recent emerging concept of all-cellulose composites within the field of
environmentally friendly materials has received increasing attention. The main
advantage of these materials is the lack of using additional bonding agents such as
polymer resins as in the case of e.g. phenolic resin based panel products or natural
fibre reinforced plastics that increase their environmental impact. Two different
routes for the production of all-cellulose composites have been followed. The
obtained materials were characterised by scanning electron microscopy, X-ray
diffraction, flexure and tensile mechanical tests, thermogravimetric analysis,
pycnometry and water absorption tests.
The first strategy makes use of the selective dissolution method where the
cellulose fibre skins are partially dissolved to form a matrix phase that bonds the
fibres together, while the strong core fibres are maintained and impart a reinforcing
effect to the composites. The influence of the dissolution time, activation time and
the fibre source were assessed. It was found that a dissolution time of 18 h led to
materials with the best overall mechanical performance (5.5 GPa and 145 MPa for
Young’s modulus and tensile strength, respectively), as this time allowed for the
dissolution of a sufficient amount of fibre surface to obtain good interfacial bonding
between fibres, while keeping a considerable amount of remaining fibre cores that
provide a strong reinforcement to the composite, leading to materials that outperform
natural fibres reinforced polypropylene composites.
Still, the previous methodology has the drawback of using chemical
substances of high environmental impact (solvents). In order to overcome this, a new
concept in the production of all-cellulose composites is proposed in this work, which
makes use of the intrinsic bonding capability between cellulose fibres to enhance the
hydrogen bond network in order to produce materials of good mechanical
performance. A new experimental procedure was developed, based on the refinement
Abstract
5
of cellulose fibres in order to increase their specific surface area, thus increasing the
interfibre bonding capability, and achieving materials with excellent mechanical
properties, up to 17 GPa and 119 MPa for flexural modulus and strength,
respectively, and low water absorption. These new high-performing environmentally
friendly materials are based on renewable resources and are 100% recyclable and
biodegradable.Financial support from the Engineering and Physical Sciences Research
Council through a Technology Strategy Board project REFLECT no. MATH1E2R,
under the Design & Manufacture of Sustainable Products Call, is gratefully
acknowledged
The Formulation of Titanium - based Metal Feedstocks and the Fabrication of Parts using the Powder Injection Moulding Process
No full textDevelopment of a profitable titanium industry for New Zealand will not come about without innovative technologies. Plastic injection moulding has long held a place in NZ manufacturing to produce large quantities of complex parts and holds the key to such innovation.
Titanium metal parts were fabricated by injection moulding titanium based metal powder feedstock followed by a debinding process and subsequent sintering. The fabrication process in its entirety was investigated in four distinct steps. Feedstock formulation involved combining the metal powders with various carrier components. Injection moulding enabled the shaping of the feedstock into geometries approximating the final part. Debinding being the process whereby the carrier/binder system is removed from the part to create a powder compact retaining the required geometry. Sintering being the final step where the metal powders are consolidated into a fully dense metal part of net shape.
The feedstock binder consisted of water soluble polyethylene glycol that reduced feedstock viscosity, improved particle wetting, aided greenpart shape retention and eliminated toxic solvents in debinding. Carnauba wax and bees wax aided dispersion, lubricated particles, were safe to handle and better for the environment (than petroleum waxes). Their low melt temperatures aided removal during thermal debinding and supported residue elimination.
By optimising the ratio of water soluble, wax and polyolefin binder components (3: 2: 1 respectively) for melt flow and pellet formation, greenparts defect free with uniform particle distribution were made. The optimal binder system proved suitable for titanium alloy and irregular shape pure titanium powders (hydride-de-hydride). Increasing powder loading (wP = (0.60 to 0.65)) had no appreciable effect on viscosity while enabling feedstock with good uniformity and pellet formation. Dimensional change was not affected by uniformity of the feedstock however molecular weight, volume and dispersion of binder components affected interparticular distances. Low processing temperatures reduced disruption to part geometry, benefitted particle bonding and helped retain handling strength.
The use of low temperatures for thermal debinding (t = 250 °C) enabled removal of the binder below the temperatures that facilitate interstitial diffusion and oxide/carbide formation, although part thickness, mass and overall volume effected the processing time. A strong correlation was seen between handling strength of the greenparts and defects, such as non-uniform density distribution and cracking after sintering.
Sintering was essential to produce the final part and showed that a binder free brownpart was not the only criteria for eliminating impurities. The furnace atmosphere must remain free from contamination to eliminate transfer back to the parts. This was addressed using an argon sweep gas, however, the design and efficacy of the system was considered inadequate. Decomposition products need to be removed quickly from the furnace as they evolve before impurities from the sweep gas diffuse back into the parts during the extended duration at sinter temperatures (t = 1300 °C).
The combination of an optimised titanium feedstock and the use of a low temperature thermal debinding technique produced a consolidated MIM part of relatively large dimensions. The parts were seen to have uniform microstructure throughout the cross-section with density comparable to that of MIM standards. In difference to the literature, a high powder loading (φp = 0.65) of HDH powders was used and shown to be readily mouldable. The higher powder loading also eliminate separation defects and shape distortions evident using lower amounts of powder
Analysis of Inorganic Binder Bridges Destruction after Thermal Load
No full textRecently, the use of inorganic binders cured by heat as a progressive technology for large scale production of cores is widely discussed topic in aluminium foundries. As practical experiences show, knock-out properties of inorganic binders were significantly increased, although they cannot overcome organic based binder systems. This paper contains information about hot curing processes based on alkali silicate and geopolymer binder systems for core making. Main differences between hot cured geopolymers and hot cured alkali silicate based inorganic binders are discussed. Theory of geopolymer binder states, that binder bridge destruction is mainly of adhesive character. The main aim of this research paper was to examine binder bridge destruction of alkali silicate and geopolymer binder systems. In order to fulfil this objective, sample parts were submitted to defined thermal load, broken and by using SEM analysis, binder bridge destruction mechanism was observed. Results showed that geopolymer binder system examined within this investigation does not have mainly adhesive destruction of binder bridges, however the ratio of adhesive-cohesive to cohesive destruction is higher than by use of alkali silicate based binder systems, therefore better knock-out properties can be expected
Bituminous Binder and Bituminous Mixture Modified with Waste Polyethylene
No full textRILEM TC-279 WMR task group TG 1 studied the performance of waste Polyethylene (PE) in bituminous binders and bituminous mixtures. Several laboratories participated in this study following a common protocol. Locally sources aggregates and bituminous binder and same source of waste PE were utilized. The binder experiments showed that at high temperatures, using MSCR tests, PE modified blends had better resistance to permanent deformation in comparison to the non modified binder. Whereas at intermediate temperatures, using the LAS tests, fatigue performance of the PE blends could withstand more loading cycles under low strains; however, it could sustain less loading cycles under high strains due to the increase in brittleness. Dry process was used for the mixture experiments in order to bypass the stability and inhomogeneity experience that was observed at the binder scale. The PE modified mixtures showed improved workability and increased strength. The higher the PE dosage, the higher the ITS increase with respect to the values measured for the control materials (i.e., without any plastic waste) thanks to the improved cohesion of the plastic modified mastic. The stiffness experiments tended to show an improved performance with a lower time dependence and a higher elasticity when plastic was added. The cyclic compression tests demonstrated a reduced creep rate along with a higher creep modulus thanks to the addition of PE; similar conclusions can be drawn from the experimental findings coming from wheel tracking test. Furthermore, acceptable and often improved moisture resistance was observed for PE modified materials.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Pavement Engineerin
Extração, assistida por plasma, de ligantes orgânicos de peças produzidas por injeção de pós: estudo da extração dos componentes de baixo peso molecular
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2008Com o advento da tecnologia Moldagem de Pós por Injeção (MPI) a fabricação de peças pequenas, complexas, com alta precisão e baixo custo ganhou uma importância comercial crescente nos setores metálicos das principais indústrias tais como a automobilística, médica, aeroespacial e defesa. Usando pós, misturados com ligantes orgânicos apropriadas, MPI transfere flexibilidade, facilidade do uso, e o custo relativamente baixo da moldagem por injeção de plástico aos setores metálicos e cerâmicos. O longo tempo de processamento para obter o produto acabado é, entretanto, uma das principais limitações da utilização mais difundida dessa tecnologia, para a qual uma das principais limitações é a fase de extração, que consiste em remover o ligante orgânico das peças que foram moldadas. A necessidade de extrair com cuidado o ligante, e ao mesmo tempo evitar a deformação devido ao rompimento das partículas do pó, é uma das razões do longo tempo de processamento. Este trabalho de pesquisa demonstra a possibilidade de se utilizar o processo de extração e sinterização assistida por plasma (PADS) como uma adição ao estágio de extração. O sistema ligante utilizado foi baseado em parafina (PW), etil vinil acetato (EVA) e polipropileno (PP). Os experimentos de extração foram realizados variando sistematicamente o tempo de extração, temperatura e a área catódica, de 50 a 100 cm². Os resultados mostraram que a incorporação da extração e sinterização em um mesmo forno traz vantagens relativas à economia de energia, consumo de gás e tempo de processamento. O PADS pode ser usado para extração total do sistema ligante, mas algumas mudanças precisam ser feitas a respeito do sistema de ligante para se obter resultados apropriados de extração. Além disso, os resultados mostram que a taxa de extração da parafina, presente no sistema de ligante atual, pode ser melhorada aumentando a quantidade de elétrons presentes no ambiente do plasma. Tal aumento na geração do elétron pode ser promovido aumentando-se a área catódica.With the advent of Powder Injection Molding (PIM) technology the anufacturing of small, complex, high-precision and low-cost parts has gained increasing commercial importance in the metallic sectors of major industries such as automobile, medical, aerospace and defense . By using powders, mixed with appropriate organic binders, PIM transfers flexibility, ease of use, and relatively low cost of plastic injection molding to the metallic and ceramic worlds. The long processing time to get a finished product is, however, one of the main restrictions to a more widespread use of this technology, for which a crucial step is the debinding phase, that consists of removing the organic binders from the parts once they have been molded. The need to carefully extract the binder, and at the same time avoid part deformation due to disruption of powder particles, is one of the reasons of such long processing times. This research works demonstrate the possibility of using plasmaassisted debinding and sintering (PADS) process as an add to the debinding stage. The binder system used was constituted of paraffin wax (PW), ethylenevinyl acetate (EVA) and polypropylene (PP). The debinding experiments were carried out varying systematically debinding time, temperature and cathodic area, from 50 to 100 cm². Results have shown that the incorporation of debinding and sintering in the same furnace bring advantages regarding energy savings, gas consumption and processing time. PADS can be extended to full-debinding of feedstocks, but some hanges must be undertaken regarding the binder system in order to obtain proper results in terms of binder extraction. Moreover results show that the debinding rate of paraffin wax, present in the actual binder system, can be improved by increasing the amount of electrons present in the plasma environment. Such an increase in electron generation can be promoted by increasing the cathodic area
I. Sonate
No full textfür das Pianoforte / componiert von Adolf Ant. Binder. - [Autograph] - [s.l.], 1871. - [9 Bl.] ; 31 x 25 cm - (Nachlass Adolf Binder)
14-zeiliges Notenpapier, schwarze Tinte, blauer Farbstift.für das Pianoforte / componiert von Adolf Ant. Binder. - [Autograph] - [s.l.], 1871. - [9 Bl.] ; 31 x 25 cm - (Nachlass Adolf Binder)
14-zeiliges Notenpapier, schwarze Tinte, blauer Farbstift
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