Impact, Deformation and Cooling Down of Atmospheric Induction Plasma Sprayed Ceramic Particles and Their Influence on Coating Properties

Abstract In the present work ceramic particles (Al2O3, YSZ) are sprayed onto steel substrates using a radio frequency inductively coupled atmospheric plasma spray process (IC APS). Because of the low plasma velocity and the large plasma volume large particles can be completely melted. The particles reach the substrate with low velocities (in the order of 10 m/s). So, a special kind of deformation can be observed. Some characteristic values of impact and deformation are also quite different from some other thermal spraying technologies. Of course, that has an strong influence on the coating properties. It is shown, that a high kinetic energy of impinging particles is not an essential assumption for a high bond strength and a low porosity of the coatings. IC Plasma sprayed particle splats are investigated and compared with DC and HVOF sprayed ones. The influence of the particle impact and deformation on the coating properties is demonstrated. It is shown, that in spite of the low particle velocities coatings can be sprayed by IC APS with comparable quality, but with quite different coating properties such as the crystalline structure.</jats:p

Microstructural Comparison of Alumina Coatings Prepared by RF and DC Plasma Spraying

Abstract DC plasma spraying has been widely recognized as a quick and economic way to produce all kinds of coatings (metals, alloys, and ceramics) for a variety of applications. There has been a growing interest in using radio frequency (RF) plasmas. Studies have been reported on characterization of plasma-sprayed coatings by TEM, including thermal barrier coatings, alumina coatings, and Ni-Al coatings. There are, however, no detailed studies reported on microstructural comparisons of coatings prepared by RF and DC plasma spraying. In this paper, XRD, SEM, TEM, polarizing OM, four-point bending fracture, and molten particle impact behavior are used to clarify microstructural differences between the RF- and DC-coatings. The results showed that the microstructures were much different for both cases, especially in the interfacial region between the coatings and the substrates. Paper includes a German-language abstract.</jats:p

Interpreting influence: towards reflexivity in penal policymaking?

This chapter explores the contribution to be made by interpretive political analysis (IPA) in understanding the extent to which participants in penal policymaking can be considered to be reflexive. Further, it considers the extent to which IPA might facilitate the improvement of reflexivity amongst penal policymakers. Relevant forms of reflexivity are first set out. Research conducted for the monograph Dangerous Politics (Annison, 2015) is then drawn upon in order to explore this issue empirically. In closing, the potential value of IPA to the improvement of penal policymaking, via a promotion of individual and collective reflexivity, is discussed

To meet grand challenges, agricultural scientists must engage in the politics of constructive collective action

Agriculture now faces grand challenges, with crucial implications for the global future. These include the need to increase production of nutrient‐dense food, to improve agriculture's effects on soil, water, wildlife, and climate, and to enhance equity and justice in food and agricultural systems. We argue that certain politics of constructive collective action—and integral involvement of agricultural scientists in these politics—are essential for meeting grand challenges and other complex problems facing agriculture in the 21st century. To spur reflection and deliberation about the role of politics in the work of agricultural scientists, we outline these politics of constructive collective action. These serve to organize forceful responses to grand challenges through coordinated and cooperative action taken by multiple sectors of society. In essence, these politics entail (1) building bonds of affinity within a heterogenous network, (2) developing a shared roadmap for collective action, and (3) taking sustained action together. These emerging politics differ markedly from more commonly discussed forms of political activity by scientists, e.g., policy advisory, policy advocacy, and protest. We present key premises for our thesis, and then describe and discuss a politics of constructive collective action, the necessary roles of agricultural scientists, and an agenda for exploring and expanding their engagement in these politics.24-3