Quantitative <i>In Situ</i> Study of the Dehydration of Bentonite-Bonded Molding Sands

Jordan, Guntram; Eulenkamp, Constanze; Calzada, Elbio; Schillinger, Burkhard; Hoelzel, Markus; Gigler, Alexander M.; Stanjek, Helge; Schmahl, Wolfgang W.

doi:10.1346/ccmn.2013.0610210

Cited by 7 publications

(6 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The composition of the prepared moulding sands is presented in Table 1. The proportions of the molding sands were selected in terms of the use of the smallest amount of binder for their preparation, in accordance with the assumption that the best molding sand is the one that contains as little binding material as possible [1,28]. Three types of standard laboratory specimens were made: cylindrical, elongated and eight-shaped (dog bone) [1].…”

Section: Methodsmentioning

confidence: 99%

Archives of Foundry Engineering

Samociuk,

Gal,

Nowak

2020

View full text Add to dashboard Cite

The foundry industry is looking for solutions that improve the quality of the finished product and solutions that reduce the negative impact of the industry on the natural environment [26]. This process leads to work on the use of new or previously unused materials for binders. Organic and inorganic foundry binders are replaced by renewable materials of plant origin to meet the requirements of both the foundry customers and the environmental and health and safety regulations. The aim of this work was to identify the applicability of renewable and organic malted barley binder in moulding sand technology. The influence of the malt binder content on dry tensile strength, dry bending strength, dry permeability, dry wear resistance and flowability were evaluated. The results show that the malted barley binder can be selfcontained material binding the high-silica sand grains. Selected mechanical properties of moulding sands were found to increase with an increase in binder content. It was observed that malted barley binder creates smooth bonding bridges between high-silica sand grains.

show abstract

Section: Methodsmentioning

confidence: 99%

Archives of Foundry Engineering

Samociuk,

Gal,

Nowak

2020

View full text Add to dashboard Cite

show abstract

“…Analysis of comparable bentonite from the same source yielded approx. 87 wt% smectite and 13 wt% of other minerals (mainly feldspar, quartz, and calcite; Jordan et al, 2013).…”

Section: Methodsmentioning

confidence: 99%

Effects of heat and cyclic reuse on the properties of bentonite-bonded sand

Schiebel¹,

Jordan²,

Kaestner³

et al. 2018

ejm

Self Cite

View full text Add to dashboard Cite

Bentonite-bonded quartz sand is the most common mould material used in foundry industry. During casting, however, the moulding sand undergoes alterations, which deteriorate its properties. Aim of this work, therefore, was to gain accurate insights into the relation between smectite alteration and property change. To this end, the wet tensile strengths of heat pre-treated and cyclically reused sands were related to the kinematics of water within the sand as measured by in-situ neutron radiography and neutron diffraction. Sands subjected to 22 cycles of drying (T = 120°C) and remoistening (3 wt%) revealed modifications of the d values of the basal reflections of smectites. No significant change of tensile strength, however, was associated with these modifications. Contrarily, sands pre-treated with temperatures as low as 225°C revealed a reduction of tensile strength, which was neither correlated to the loss of tightly bound water nor to dehydroxylation. For temperatures above 300°C a correlation between the reduction of tensile strength and the loss of tightly bound water or early dehydroxylation was evident. With completing dehydroxylation of the smectites above 670°C, total loss of wet tensile strength of the pre-heated sands was observed. The results showed that cyclic use of moulding sand had little impact on the sand quality as long as the temperature of the sand remained low. For the practice in foundry, the results imply that a rigorous separation of heat-exposed sand is advantageous.

show abstract

“…The attenuation of neutrons by most elements forming silicate minerals (Si, Al, Ca, Fe, Mg, Na, O ...) is orders of magnitudes smaller than attenuation by hydrogen. Neutron radiography, therefore, can quantify water transfer within porous media such as quartz sands, concretes, plants, rocks and soils in situ Shokri et al 2008;Schillinger et al 2011;Sedighi-Gilani et al 2013;Shokri and Or 2013;Hall 2013;Jordan et al 2013;Villman et al 2014;Boon et al 2015). In combination with temperature measurements and mechanical testing, neutron radiography is not only a suitable method to investigate the coupling of heat and moisture transport but also to assess the relation between transport and material property.…”

Section: Introductionmentioning

confidence: 99%

“…In combination with temperature measurements and mechanical testing, neutron radiography is not only a suitable method to investigate the coupling of heat and moisture transport but also to assess the relation between transport and material property. Furthermore, if water is the only mobile phase, plots of local moisture content vs. temperature can be taken as local thermogravimetric measurements within a large-scale sample (Jordan et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Neutron Radiographic Study of the Effect of Heat-Driven Water Transport on the Tensile Strength of Bentonite-Bonded Moulding Sand

et al. 2017

Self Cite

View full text Add to dashboard Cite

Wet tensile testing is a common method to assess the stability of bentonite-bonded moulding sands. For wet tensile testing, a specimen is first heated from above in order to simulate heat-driven moisture transport induced by the casting process. Then, tensile stress is applied until rupture. In this study, neutron radiography imaging was applied to moulding sands in situ during heating and wet tensile testing in order to investigate the effects of water kinematics on the tensile strength. Neutron radiography allowed the localization of the rupture plane and the quantitative determination of the local water content with sub-mm resolution. Quantification of the temperature at the rupture plane and of the heat kinematics within the specimen was accomplished by temperature measurements both in situ and ex situ. In this way, experimental data correlating the wet tensile strength with the specific conditions of moulding sands at the rupture plane were obtained for the first time. that the weakest location within a sand profile can be pinpointed at the interface between evaporation and condensation zone (i.e. at the 100 • C isotherm), where water vaporization starts and the water bridges connecting the sand grains collapse. This weakest location has maximum strength, if the local water content at the rupture plane is between 5 and 9 wt.%. Less water leads to a strong decrease of wet tensile strength. More water requires an initial water content above 5 wt.%, which leads to a decrease of the tensile strength of the unheated sand.

show abstract

Quantitative In Situ Study of the Dehydration of Bentonite-Bonded Molding Sands

Cited by 7 publications

References 33 publications

Archives of Foundry Engineering

Archives of Foundry Engineering

Effects of heat and cyclic reuse on the properties of bentonite-bonded sand

Neutron Radiographic Study of the Effect of Heat-Driven Water Transport on the Tensile Strength of Bentonite-Bonded Moulding Sand

Contact Info

Product

Resources

About