Laser powder bed fusion additive manufacturing of copper wicking structures: fabrication and capillary characterization

PurposeAn integral component in heat pipes (HPs) and vapor chambers (VCs) is a porous wicking structure. Traditional methods for manufacturing wicking structures within HPs and VCs involve secondary manufacturing processes and are generally limited to simple geometries. This work aims to leverage the unprecedented level of design freedom of laser powder bed fusion (LPBF) additive manufacturing (AM) to produce integrated wicking structures for HPs and VCs.Design/methodology/approachCopper wicking structures are fabricated through LPBF via partial sintering and via the formation of square, hexagonal and rectangular arrangements of micro-pins and micro-grooves, produced in multiple build directions. Wicks are characterized by conducting capillary performance analysis through the measurement of porosity, permeability and capillary rate-of-rise.FindingsCopper wicking structures were successfully fabricated with capillary performance, K/reff, ranging from 0.186–1.74 µm. The rectangular-arrangement micro-pin wick presented the highest performance.Originality/valueThis work represents the first published report on LPBF AM of copper wicking structures for HPs/VCs applications and represents foundational knowledge for fabricating complete assemblies of copper VCs and HPs through LPBF AM.

Laser powder bed fusion additive manufacturing of copper wicking structures: fabrication and capillary characterization

Purpose An integral component in heat pipes (HPs) and vapor chambers (VCs) is a porous wicking structure. Traditional methods for manufacturing wicking structures within HPs and VCs involve secondary manufacturing processes and are generally limited to simple geometries. This work aims to leverage the unprecedented level of design freedom of laser powder bed fusion (LPBF) additive manufacturing (AM) to produce integrated wicking structures for HPs and VCs. Design/methodology/approach Copper wicking structures are fabricated through LPBF via partial sintering and via the formation of square, hexagonal and rectangular arrangements of micro-pins and micro-grooves, produced in multiple build directions. Wicks are characterized by conducting capillary performance analysis through the measurement of porosity, permeability and capillary rate-of-rise. Findings Copper wicking structures were successfully fabricated with capillary performance, K/reff, ranging from 0.186–1.74 µm. The rectangular-arrangement micro-pin wick presented the highest performance. Originality/value This work represents the first published report on LPBF AM of copper wicking structures for HPs/VCs applications and represents foundational knowledge for fabricating complete assemblies of copper VCs and HPs through LPBF AM.

Environmental protection policies at craft villages in Hanoi in the context of sustainable development

Craft village is one of the distinct features of rural areas and an important factor in industrial and secondary manufacturing zones and subzones in Vietnam. Craft village, in nature, is a guild within a village who earn their living through non-agricultural activities. Craft village has been long preserved and developed with various characteristics including production subject (artisan); produce (featured by sophistication and arts); natural condition and specific technological process. In the context of industrialization and modernization being interwined with sustainable development, this article provides an insight into environmental protection policies applied to craft villages in Hanoi in order to understand the situation of executing environmental protection policies for craft villages in Hanoi; to point out challenges in formulating and implementing the policies; to therefore propose measures to develop the policies and enhance the implementation effectiveness.

Evaluation of Health Risk Level of Hand-Arm and Whole-Body Vibrations on the Technical Operators and Equipment in a Tobacco-Producing Company in Nigeria

Vibration is experienced when a body is subjected to either internal or external forces which cause oscillation, with most operators of industrial equipment often exposed to high dosage, higher than the stipulated values. In this research, Digital Real-Time Frequency Analyzer (RSA 5106A) was used, while the results obtained were evaluated and compared with the health guidelines of the ISO 2631-1 : 1997 and ISO 2631-5 : 2004 standards, as described in the Health Guidance Caution Zone for a daily exposure action value (EAV) of 0.47 m/s2 and a daily exposure limit value (ELV) of 0.93 m/s. High acceleration was mostly seen on the z-axis in all the results obtained, whereas many were not within the HGCZ (Arms <0.47, and >0.93 m/s2). Comparing (VDV <8.5 m/s1.75 and >17 m/s1.75) with the ISO standard, the accelerations on all x- and y-axes were slightly within the HGCZ, with just a little below 0.47 m/s2 limit. The results obtained clearly showed that urgent action is needed virtually on all the equipment in both the Secondary Manufacturing Department (SMD) and Primary Manufacturing Department (PMD) to minimize vibration exposure on the technical operators.

Synthesis and Mechanical Property Evaluation of Hot Forged Aluminium Alloy Reinforced with Nano Alumina

Metal matrix composites with aluminium matrix and non-metallic reinforcements are popular candidates in automotive, aerospace, sports and military application because of their high strength-to-weight ratio, stiffness, wear resistance, high-temperature resistance, etc. often they are subjected to secondary manufacturing processes like extrusion, rolling, forging, etc. to suit the service requirements. Metal matrix composites reinforced by nanoparticles are very promising materials, suitable for a large number of applications. In the present investigation, nanocomposites have been synthesized by addition of 0.25, 0.5, 0.75, 1 and 1.25 wt% of nanoAl2O3 powder in to molten Al 1100-Mg alloy using stir casting method and then hot forged. The mechanical properties such as tensile strength, hardness and percentage elongations were studied for all the test specimens. The 0.75 wt% of nanoAl2O3 added forged nanocomposite exhibited higher hardness and 0.5 wt% of nanoAl2O3 added forged nanocomposite exhibited higher yield strength, tensile strength and percentage of elongation.

An Analysis of Trends in Foreign Direct Investment Inflows to Africa

This study examines the trends in Foreign Direct Investment (FDI) inflows to Africa, with the ultimate aim of proposing implications for policy action. The main source of data for this study is the UNCTAD (2018) database which at the time of the study contained FDI data from 1990 to 2016. The findings show that, although Africa is in dire need for FDI due to scarcity of capital, it is not able to attract as much FDI compared to advanced countries and other developing regions. The little FDI that comes to Africa is concentrated sub-regionally and country-wise. Region-wise, most FDI is concentrated on Southern Africa followed by Northern Africa with East Africa and Central Africa at the bottom. Country-wise, the two main recipients of FDI in each sub-region are Angola and South Africa (Southern Africa); Egypt and Morocco (North Africa); Nigeria and Ghana (West Africa); Tanzania and Ethiopia (East Africa) and Congo and the Democratic Republic of Congo (Central Africa). The FDI that comes into the continent is further concentrated in the primary (extractive) sector. As a result the benefits to the region have not been as significant as in East Asia where FDI was mainly into the secondary (manufacturing) sector. It is concluded that, FDI is a growth point that countries can count on as a source of resources for development, however, Africa need to change the approach adopted in promoting FDI, which focuses on providing incentives to creating a domestic environment conducive to entrepreneurship and business in general.