Is diamond the hardest substance on Earth? or Is CBN harder than Diamond? Most of us don’t know that this claim was only a myth sixty years ago. With the help of technological advancement, mineralogists made an impressive discovery that may alter the diamond's throne as the strongest substance on the planet. And that is the Cubic Boron Nitride or CBN. Is CBN harder than Diamond? That is what we’re going to find out.
What is Cubic Boron Nitride (CBN)?
CBN or Cubic Boron Nitride is a man-made synthetic abrasive made from cubic boron nitride grains bonded by ceramic material. It shares the same crystalline structure as diamond. The only difference is, that the carbon atoms are made up of alternately bonded atoms of boron and nitrogen. Although it shares similar properties with diamond, it is much superior chemical and thermal stability compared to diamond.
How is CBN Manufactured?
Cubic Boron Nitride is similarly manufactured with artificial diamonds through the sintering process or frittage method. The sintering process involves adding heat to the mineral for it to convey strength and integrity to the substance.
What is a Diamond?
Diamond, as we all know, is the hardest material on earth. The hardness of the diamond provides incredible cutting abilities which kept it in high demand for more than a thousand years. Diamond is a special form of carbon where it is made up of strong chemical atom bonds which makes the whole structure an extremely rigid crystal. This is the reason why diamond is considered the hardest substance.
How is Diamond Produced?
Compared to CBN, diamond is naturally formed under conditions of intense heat and pressure that causes carbon atoms to crystallize and formed into diamonds.
Is CBN Harder than Diamond?
When it comes to hardness, CBN is quite similar to diamond based on the Mohs scale and other hardness scales. But between the two materials, diamond is considerably harder at room temperature with a hardness range of 7,500 compared to CBN hardness of 4,500. On the other hand, CBN is considered the second hardest material on Earth and has better thermal and chemical stability, which is appropriate for grinding steels. Compared to diamond, CBN is also much more suitable for lapping operations on ferrous materials. In general, the question, "Is CBN harder than Diamond?" will be determined by comparing the two substances in terms of grinding wheel development.
Comparing CBN and Diamond in Terms of Grinding Wheel Development
In terms of choosing the appropriate abrasive for grinding, it is important to have a careful comparison between diamond and cubic boron nitride (CBN). Hardness is a very important property of a material and is usually used to determine its function. This is why comparing diamond and cubic boron nitride by weighing various aspects of the grinding wheel application is a smarter move before you conclude anything.
The first thing you have to look at is the mechanical action of the grinding method with super abrasive grit particles. This will determine if the material can remove material in a unique way. For CBN and diamond, oftentimes it is composed of single crystals grits. In some cases, there is a possibility of using polycrystalline CBN grit such as the GE 550 series, which is recommendable for micro-chip operation and sharp edges results.
With this, CBN is replacing conventional abrasives much faster than other materials. It is being applied for the precision grinding of hardened steels due to its low rate of wear and the ability to hold close size tolerance on the produced parts.
Application: CBN vs Diamond Grinding Wheel
Diamond Application:
- With the superb hardness of diamond, it is always recommended for shaping extremely hard workpiece materials such as ceramics, carbides, stone, and glass. However, it is not recommended for steel production since there is a possibility of rapid erosion of the diamond grit which quickly damages the grinding wheel.
CBN Application:
- CBN is highly applicable for higher-speed operations since it easily generates high temperatures. Plus, its unreactive nature makes it the preferred choice for grinding steels like tool steels.
Is CBN harder than Diamond? The answer is, No. Diamond is still the hardest substance on earth. It is still the most recommended material for tough grinding applications.
Both diamond and CBN grinding wheels have their advantages and disadvantages. To sum up, this whole blog, remember to use diamond grinding wheels on grinding the hardest workpiece materials at a moderate temperature. Use CBN on ferrous workpiece material to avoid chemical reactions to prevent it from wearing out faster. For more related details about CBN Grinding Wheels, click here. For Diamond Grinding Wheel, click here. For other grinding wheels, visit our website at agrindtool.com.