There are provided an X-ray generating apparatus capable of switching X-ray beams of high energy and low energy to each other at high speed, and an X-ray CT apparatus capable of performing high-speed and high-quality multi-energy imaging by using the same. The connection apparatus comprises a first and a second connection part. , arrayed waveguide gratings, combined with a set of transmitter cards. Also, according to inclining a face 24 at an inner circumferential side of the connection holding section 21, a pitch and a space of a sealing section 31 are changed. The angle sensor 21 can include a first angle sensor which can detect an angular range of the first cam face, and a second angle sensor which can detect an angular range of the second cam face. 1 wt % to about 18 wt % slurry sintering aid, and environmental barrier coatings including such compositions.