B. Fiegl, M. Hibler, W. Kiffe, F. Koch, R. Kuhnert, R. Messer and H. Schwarzbauer
Module technology has become the most successful technology for power devices. The sandwich structure of the module serves as both an electrical insulator and heat sink to remove…
Abstract
Module technology has become the most successful technology for power devices. The sandwich structure of the module serves as both an electrical insulator and heat sink to remove the heat generated in the device. Typical heat fluxes of 200 W/cm2 through the chip substrate interface make it necessary to develop modules with a lower thermal resistance than those available today. With the recent advances in diamond technology, diamond substrates which have unique heat conducting properties are now available. Presented here are the first applications of diamond films in power device modules in combination with a new joining technology. The thermal behaviour of these modules has been simulated. Following the simulations, power device modules with a diamond film were produced. Investigations with a scanning acoustic microscope showed that there is good mechanical contact between the diamond and the adjacent layers. The thermal resistance of the modules was measured. The results are in good agreement with those of the simulations. They show that the application of diamond films in power modules for heat conduction and heat spreading is feasible. It is demonstrated that diamond films together with an advanced joining technology provide a considerable improvement in thermal management compared with state‐of‐the‐art technologies.
Mehmet Kivanc Turan, Muhammet Üsame Sabirli, Altug Bakirci, Emirhan Kartal and Fatih Karpat
This study aims to investigate the effects of five different printing parameters, namely, printing speed (PS), printing temperature/nozzle temperature/extrusion temperature…
Abstract
Purpose
This study aims to investigate the effects of five different printing parameters, namely, printing speed (PS), printing temperature/nozzle temperature/extrusion temperature, heated-bed temperature, raster angle (RA) and layer height (LT), on mechanical properties.
Design/methodology/approach
American Society for Testing and Materials (ASTM) standards were used for the specimen design. Then, the Taguchi method was used for the design of the experiment and an L16 orthogonal array was preferred. Tensile, Shore D and surface roughness tests were conducted on polylactic acid test specimens. The test results were analyzed using the signal-to-noise ratio and analysis of variance (ANOVA).
Findings
As a result of the study, it was seen that RA is the most important parameter for the tensile strength, PS is for the hardness and LT is for the surface roughness. According to the ANOVA results, the effects of the RA, PS and LT on the maximum tensile strength, hardness and surface roughness were 41.59%, 69.51% and 44.6%, respectively.
Originality/value
To the best of the authors’ knowledge, this study is one of the most comprehensive parameter optimization studies for additive manufacturing in the literature because it includes five different printing parameters and three mechanical test procedures.
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Bernard Cova and Véronique Cova
This paper presents an alternative, “Latin” vision of our societies. Here the urgent societal issue is not to celebrate freedom from social constraints, but to re‐establish…
Abstract
This paper presents an alternative, “Latin” vision of our societies. Here the urgent societal issue is not to celebrate freedom from social constraints, but to re‐establish communal embeddedness. The citizen of 2002 is less interested in the objects of consumption than in the social links and identities that come with them. This Latin view holds that people like to gather together in tribes and that such social, proximate communities are more affective and influential on people’s behaviour than either marketing institutions or other “formal” cultural authorities. There is also an element of resistance and re‐appropriation in the acts of being, gathering and experiencing together. This view of the shared experience of tribes sets it apart from both Northern notions of segmented markets and one‐to‐one relationships. In this Latin view, the effective marketing of 2002 and beyond is not to accept and exploit consumers in their contemporary individualisation, as Northern approaches might. Rather the future of marketing is in offering and supporting a renewed sense of community. Marketing becomes tribal marketing. In a marketing profession challenged by the Internet phenomenon, tribal marketing is by no means just another passing fad but a Trojan horse to induce companies to take on board the re‐emergence of the quest for community.
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Arad Azizi, Fatemeh Hejripour, Jacob A. Goodman, Piyush A. Kulkarni, Xiaobo Chen, Guangwen Zhou and Scott N. Schiffres
AlSi10Mg alloy is commonly used in laser powder bed fusion due to its printability, relatively high thermal conductivity, low density and good mechanical properties. However, the…
Abstract
Purpose
AlSi10Mg alloy is commonly used in laser powder bed fusion due to its printability, relatively high thermal conductivity, low density and good mechanical properties. However, the thermal conductivity of as-built materials as a function of processing (energy density, laser power, laser scanning speed, support structure) and build orientation, are not well explored in the literature. This study aims to elucidate the relationship between processing, microstructure, and thermal conductivity.
Design/methodology/approach
The thermal conductivity of laser powder bed fusion (L-PBF) AlSi10Mg samples are investigated by the flash diffusivity and frequency domain thermoreflectance (FDTR) techniques. Thermal conductivities are linked to the microstructure of L-PBF AlSi10Mg, which changes with processing conditions. The through-plane exceeded the in-plane thermal conductivity for all energy densities. A co-located thermal conductivity map by frequency domain thermoreflectance (FDTR) and crystallographic grain orientation map by electron backscattered diffraction (EBSD) was used to investigate the effect of microstructure on thermal conductivity.
Findings
The highest through-plane thermal conductivity (136 ± 2 W/m-K) was achieved at 59 J/mm3 and exceeded the values reported previously. The in-plane thermal conductivity peaked at 117 ± 2 W/m-K at 50 J/mm3. The trend of thermal conductivity reducing with energy density at similar porosity was primarily due to the reduced grain size producing more Al-Si interfaces that pose thermal resistance. At these interfaces, thermal energy must convert from electrons in the aluminum to phonons in the silicon. The co-located thermal conductivity and crystallographic grain orientation maps confirmed that larger colonies of columnar grains have higher thermal conductivity compared to smaller columnar grains.
Practical implications
The thermal properties of AlSi10Mg are crucial to heat transfer applications including additively manufactured heatsinks, cold plates, vapor chambers, heat pipes, enclosures and heat exchangers. Additionally, thermal-based nondestructive testing methods require these properties for applications such as defect detection and simulation of L-PBF processes. Industrial standards for L-PBF processes and components can use the data for thermal applications.
Originality/value
To the best of the authors’ knowledge, this paper is the first to make coupled thermal conductivity maps that were matched to microstructure for L-PBF AlSi10Mg aluminum alloy. This was achieved by a unique in-house thermal conductivity mapping setup and relating the data to local SEM EBSD maps. This provides the first conclusive proof that larger grain sizes can achieve higher thermal conductivity for this processing method and material system. This study also shows that control of the solidification can result in higher thermal conductivity. It was also the first to find that the build substrate (with or without support) has a large effect on thermal conductivity.
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Donald J. Willower and Cynthia L. Uline
Examines the alleged demise of science in terms of claimed difficulties including: the human limitations of scientists, that science seeks ultimate reality and universal truth…
Abstract
Examines the alleged demise of science in terms of claimed difficulties including: the human limitations of scientists, that science seeks ultimate reality and universal truth, oversimplifies complexity, and accepts no standard external to itself. Also considers incommensurability, the theory ladeness issue, and the assumption of orderliness. Overall, there is little discussion of epistemological issues in the sense of exploring pros and cons, while the resurrection of positivism and its equation with science and “big tent” thinking that confers legitimacy on every interest group’s position regardless of its cogency, further degrades discourse. The naturalistic‐pragmatist perspective presented as an alternative sees scientific inquiry as an open, growing, fallible activity that has proven far superior to other methods of problem solving. Inquiry is also taken to be central to principled moral choice and to efforts aimed at improving people’s lives.
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Marko Järvenpää and Aapo Länsiluoto
The purpose of this paper is to examine how collective identity and institutional logic affect the design and use of an environmental performance measurement system.
Abstract
Purpose
The purpose of this paper is to examine how collective identity and institutional logic affect the design and use of an environmental performance measurement system.
Design/methodology/approach
The authors use a qualitative case study with abductive theorizing and empirical data obtained through semi-structured interviews, observation and document analysis.
Findings
The new environmental measures were reshaped by aligning them with the existing and dominant collective identity in the case organization – in other words, cost savings and profitability. Moreover, the institutional logic forced the environmental measures to remain as non-strategic and non-bonus criteria in favour of traditional financial measures.
Originality/value
Thornton and Ocasio’s (2008) institutional logic is applied and its potential for analyzing change in environmental accounting is shown. The paper illustrates how collective identity and institutional logic are important mechanisms reshaping environmental performance measurement design and use, when the existing collective identity is reproduced.