What is the difference between iPhone 9D and 9H tempered film?

9H refers to hardness and 9D refers to the curvature of the membrane.
But there is no real 9D, no matter how many D tempered films are only divided into three curvatures: plane, 2.5D, and 3D.
9H refers to the hardness, which actually refers to the hardness of the pencil, not the Mohs hardness. Even a piece of glass can exceed this hardness, which is also a marketing gimmick.

Hardness is divided into:
1. Scratch hardness. It is mainly used to compare the degree of softness and hardness of different minerals. The method is to select a rod with one end hard and one soft at the other, and scratch the tested material along the rod, and determine the softness and hardness of the tested material according to the position of the scratch. Qualitatively speaking, the scratches made by hard objects are longer, and the scratches made by soft objects are shorter.
2. Press-in hardness. Mainly used for metal materials, the method is to press the specified indenter into the tested material with a certain load, and compare the hardness of the tested material with the size of the local plastic deformation on the surface of the material.
Due to the difference of indenter, load and load duration, there are many kinds of indentation hardness, mainly Brinell hardness, Rockwell hardness, Vickers hardness and microhardness.

3. Rebound hardness. Mainly used for metal materials, the method is to make a special small hammer fall freely from a certain height to impact the sample of the material to be tested, and use the amount of strain energy stored (and then released) by the sample during the impact process (through the return of the small hammer). jump height determination) to determine the hardness of the material.
The Rockwell hardness test method is the American S. P. Proposed by Rockwell in 1919, it basically overcomes the above-mentioned shortcomings of the Brinell assay. The indenter used for Rockwell hardness is a diamond cone with a taper angle of 120° or a steel ball with a diameter of 1/16 inch (1 inch equals 25.4 mm), and the indentation depth is used as the basis for calibrating the hardness value.