Hardness

Japanese: 硬度 - こうど

〘noun〙① A word that expresses the degree of hardness of an object. It is mainly measured by the indentation method used to test the hardness of metals and the scratch method used to test the hardness of minerals. In the indentation method, a steel ball is pressed against the surface of the sample with a certain load, and the degree of indentation is expressed. In the scratch method, the surface of the sample is scratched with a diamond cone with a 90-degree apex angle, and the hardness is expressed by the scratches. Hardness. ※In a Town with a Castle (1925) <Kajii Motojiro> Rain "Even insects cried out, as if they were trying to repel the dense ball with a hard metal."② A word that expresses the degree of hardness of water. The amount of calcium ions and magnesium ions contained in 100cc of water is converted into the amount of calcium oxide, and one milligram is counted at one time. Water with a temperature of 20 degrees or more is called hard water, water with a temperature of 10 degrees or less is called soft water, and water between 10 and 20 degrees is called medium water. ③ A term that indicates the degree of X-ray penetration ability into an object. X-rays with a high penetrating ability and a wavelength of 0.4 angstroms or less are called hard X-rays, while those with a low penetrating ability and a wavelength of 5 to 6 angstroms or more are called soft X-rays.

Source: The Selected Edition of the Japanese Language Dictionary About the Selected Edition of the Japanese Language Dictionary Information

Japanese:

〘名〙① 物体の硬軟の程度を表わす語。主に、金属のかたさ試験に用いられる押込法と、鉱物のかたさ試験に用いる引掻法によって測る。押込法は、鋼鉄の球を一定の荷重によって試料の表面に押し付け、そのへこみぐあいによって表わし、引掻法は、頂角が九〇度のダイヤモンドの円錐体で試料の表面を引っ掻いて、その傷によってかたさを表わす。かたさ。※城のある町にて（1925）〈梶井基次郎〉雨「質の緻密な玉を硬度の高い金属ではじくやうな蟲もなき出した」② 水の硬軟の程度を表わす語。水一〇〇cc中に含まれるカルシウムイオン、マグネシウムイオンの量を酸化カルシウムの量に換算し一ミリグラムを一度とする。二〇度以上を硬水、一〇度以下を軟水、一〇～二〇度のものを中間の水という。③ Ｘ線の物体に対する透過能力の程度を表わす語。透過能力の大きい、波長〇・四オングストローム以下のものを硬Ｘ線、透過能力の小さい、波長五～六オングストローム以上のものを軟Ｘ線という。

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