Back to results
US 4,304,576 AGranted
Silicon nitride ceramic tools and a process for their production
AssigneeNgk Spark Plug Co., Ltd.
InventorsYoshinori Hattori, Masayuki Akatsuka, Yasushi Matsuo, Isamu Fukuura
Life of this patent
Estimating the term…
Abstract
A silicon nitride based ceramic tool is disclosed which is prepared from the starting powder compositions surrounded by and including the lines defined by the points A, B, and C and preferably D, E, and F in the FIGURE.
Claims4
A process for producing high durability ceramic tools, which comprises mixing Si.sub.3 N.sub.4, MgO, and stabilized zirconia powders stabilized with Y.sub.2 O.sub.3 or CaO in a mixing ratio falling within the area surrounded by and including the lines drawn between the three points of A (Si.sub.3 N.sub.4 :98 wt %;
- MgO:1 wt %;
- ZrO.sub.2 :1 wt %), B (Si.sub.3 N.sub.4 :79 wt %;
- MgO:20 wt %;
- ZrO.sub.2 :1 wt %), and C (Si.sub.3 N.sub.4 :79 wt %;
- MgO:1 wt %, ZrO.sub.2 :20 wt %) in triangular coordinates as shown in the FIGURE of the Drawing wherein the three coordinate axes indicate the weight percent Si.sub.3 N.sub.4, MgO, and stabilized ZrO.sub.2, respectively, and hot-pressing the resulting mixture at about 1,600.degree. to 1,850.degree. C. at a pressure of not less than about 100 kg/cm.sup.2 under a non-oxidizing atmosphere.
2 more elements
Dependencies are inferred from the claim text.