Judgement and Truth in Early Analytic Philosophy and Phenomenology
What is judgement? is a question that has exercised generations of philosophers. Early analytic philosophers (Frege, Russell and Wittgenstein) and phenomenologists (Brentano, Husserl and Reinach) changed how philosophers think about this question.&nb
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Laser-cladding process: a study using stationary and scanning CO laser beams 2 Y.P. Kathuria Laser X Co. Ltd., Chiryu-shi, Aichi-ken 472, Japan
Abstract In a precise and controlled laser-cladding process, the effect of power density and beam-interaction time play a vital role. We study this process in both stationary and scanning beam modes with the laser cladding of stellite 6 on mild steel, Cr–Ni base materials, and we demonstrate their effects on the evolution of coarse, fine and very fine cladding microstructure. The effect of the various parameters such as input power, beam-interaction time, scanning frequency and the traverse speed are considered. The possible applications in the rapid prototyping industries are well illustrated. © 1997 Elsevier Science S.A. Keywords: Laser; Cladding and rapid prototyping
1. Introduction In the recent past, laser cladding with the CO /Nd-YAG laser have been used successfully for 2 various applications such as hardfacing of engine valve seat, turbine engine blade shroud interlock, leading edge of steam turbine blade and rapid prototyping of metallic parts etc [1–17]. It offers the possibility for precise and controlled overlay-welding of an alloy powder, such as Ni or Co-based alloys, onto the various substrates, and it exhibits the inherent advantages of low thermal effects and less distortion compared to the conventional Tungsten Inert Gas or Plasma Arc cladding processes, resulting in a reduction in the thermal effect for the heat sensitive components. Additionally, in the conventional cladding process, the interaction time is much longer, resulting in the superheat generation [18,19] of the melt pool. This further induces the post melting and also vigorous mixing of the pool, thus producing good interfacial bonding between the substrate and the cladding, as well as more dilution, a larger heat-affected zone, and lower hardness values etc. With the lasercladding process, however, the superheat generation could effectively be controlled over the length of the interaction time thus producing less dilution, a smaller heat-affected zone, and higher hardness values etc. In the laser-cladding process, a molten pool of the pasted or blown powder, with a complex three-dimensional (3D) shape, is formed on the substrate by the laser0257-8972/97/$17.00 © 1997 Elsevier Science S.A. All rights reserved. PII S 02 5 7 -8 9 7 2 ( 9 7 ) 0 0 16 5 - 5
beam interaction with the powder material. This interaction time [20–22] plays a crucial role in obtaining the desired successful cladding so that the melting of the substrate is kept to a minimum [2]. In our present analysis, we find that in a narrow range of power density and beam-interaction time, coupled with the cooling rate and microstructure [23], the majority of the working point for laser cladding lies on the diagonal line of Fig. 1. In addition, this regime could further be classified into three main regions. The short interaction time regions (A) and (B) exhibit very fine and fine dendrite
Fig. 1. Microstructure vs. processing condi
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