Electric current activated/assisted sintering (ECAS): a review of patents 1906–2008


Published : 2009.11.20 / DOI : 10.1088/1468-6996/10/5/053001


ECAS(electric current activated sintering: 電流活性化燒結法,または spark plasma sintering: 放電プラズマ燒結法)は用途の広い燒結法として近年急速にその研究,利用が増えている.ECAS法により作成される材料,製品は質・量の改善・増大において過去20年のうちに目覚ましいものがあるにもかかわらずECAS法の装置,手法についての総合的なレビューというのは無い.この論文は,1906-2008年の過去1世紀を越える期間に公示された642件の特許を精査,ECAS技術の進展を概観し,この空白を埋めるものである. ECAS技術はBloxam(1906 GB Patent No.9020)の先駆的な抵抗加熱燒結装置の開発によって幕を開けた.特許の検索はキーワードないし関連検索を用い日本国特許庁(342件),米国特許商標庁(175件),中国知識産権局(69件),世界知的所有権機構(12件)を引き出した.この642件の中から119件を選び出し,効率,信頼性,再現性,制御性,生産性といった見地から現在のECAS装置,将来のECAS技術の基本的な概念,物理的原理,重要性を解説した.論文は2部構成で,第1部でECAS法の基本部分の基礎的概念,概要,定義などについて述べ,第2部では補助装置/周辺装置について述べた.ECAS法はさらに放電時間を参照にし,高速と超高速ECASに分類してある.ECAS法の基本原則,定義などは科学/特許文献に準拠している.


The electric current activated/assisted sintering (ECAS) is a ever growing class of versatile techniques for sintering particulate materials. Despite the tremendous advances over the last two decades in ECASed materials and products there is a lack of comprehensive reviews on ECAS apparatuses and methods. This paper fills the gap by tracing the progress of ECAS technology from 1906 to 2008 and surveys 642 ECAS patents published over more than a century. It is found that the ECAS technology was pioneered by Bloxam (1906 GB Patent No. 9020) who developed the first resistive sintering apparatus. The patents were searched by keywords or by cross-links and were withdrawn from the Japanese Patent Office (342 patents), the United States Patent and Trademark Office (175 patents), the Chinese State Intellectual Property Office of P.R.C. (69 patents) and the World Intellectual Property Organization (12 patents). A subset of 119 (out of 642) ECAS patents on methods and apparatuses was selected and described in detail with respect to their fundamental concepts, physical principles and importance in either present ECAS apparatuses or future ECAS technologies for enhancing efficiency, reliability, repeatability, controllability and productivity. The paper is divided into two parts, the first deals with the basic concepts, features and definitions of basic ECAS and the second analyzes the auxiliary devices/peripherals. The basic ECAS is classified with reference to discharge time (fast and ultrafast ECAS). The fundamental principles and definitions of ECAS are outlined in accordance with the scientific and patent literature.


Salvatore Grasso, Yoshio Sakka and Giovanni Maizza
Sci. Technol. Adv. Mater.10(2009)053001.