Active metal brazing paste composition, brazing paste, and method for brazing ceramics and metals

An active metal brazing paste composition, wherein the composition comprises a binder and metal powder;

• the metal powder comprises active metal brazing powder and brazing-aid metal powder;
• the brazing-aid metal powder comprises copper powder and/or copper-silver alloy powder;
• and the active metal brazing powder is alloy powder comprising copper, silver, and an active metal;
• and
• with a total weight of the metal powder as a reference, a content of the active metal is 1.5 wt % or more, a content of silver is 40 wt % to 90 wt %, and a content of oxygen is 0.5 wt % or less,
• wherein with a total weight of the brazing-aid metal powder as a reference, a content of oxygen of the brazing-aid metal powder is 2 wt % or less, a content of carbon of the brazing-aid metal powder is 0.75 wt % or less, and a molar ratio of oxygen to carbon in the brazing-aid metal powder is 2 or more.