The 2018 revision of the standard IEC 61400-24 : lightning protection of wind turbines

The first edition of the standard IEC 61400-24, Wind Generator Systems – Part 24 Lightning Protection, was issued in June 2010, and the scope was to reflect the experiences and technical understanding of lightning protection of wind turbines by manufacturers, certification organizations, research institutes and universities. It presented background statistical information on lightning damage to wind turbines, and it provided guidance on lightning protection best practices. Since then, the wind power industry has further developed towards even larger onshore and offshore wind turbines and into a mature industry. This is the background for the current draft of the 2018 revision of the IEC 61400-24, which transforms the 2010 edition into an evolution of the previous issued standard based on improved technical experience and expertise

Printability of gas atomized Mo-Si-B powders by laser metal deposition

Mo-Si-B alloys, as a more and more frequently considered high-temperature material, face the challenge of machining complex shapes. In the present work, the feasibility of printing pre-alloyed Mo-Si-B powder materials via laser metal deposition (LMD) process was firstly demonstrated. Mo-Si-B powder was manufactured via gas atomization (GA) process out of solid raw materials meeting the requirements for additive manufacturing (AM) regarding flowability and particle size. Investigations of the powder particles after GA and detailed analyses of the printability and microstructural evolution of the multi-phase Moss-Mo3Si-Mo5SiB2 built are presented. As a result, distinct zones resulting from the layer-wise LMD process were observed next to a microstructure of primarily solidified Moss phases embedded in fine dispersed eutectic regions. The hardness of the LMD processed material is shown to be comparable with Mo-Si-B alloys produced by ingot metallurgy (IM)