This document discusses high energy ball milling. It describes how ball milling works to grind materials through high-energy collision from balls. The process can be used to synthesize nanomaterials and modify chemical reactions. It discusses the stages of ball milling including initial flattening, intermediate fracturing and cold welding, and final refinement into a homogeneous structure. Applications include grinding chemicals for industries and producing amorphous materials. Ball milling offers advantages of low cost and adjustable capacity.

1. Alagappa University
Karaikudi-03
NAME: A. Varsha
Department: M. Sc. Nanoscience and technology

2. GRINDING
HIGH ENEGRY BALL
MILLING
Topics:

3. Grinding:
 Grinding is machining process that’s used to
remove material from a workpiece via a
grinding wheel.
 As the grinding wheel turns, it cuts material off
the workpiece while creating a smooth surface
texture in the process.
 While grinding sounds simple enough, there are
probably some things you don’t know about
this machining process. Below are five
interesting facts about grinding

5. Five facts abouts Grinding:
Lubrication Is Used to Control Chips
It Removes Material Roughly 0.25 to
0.50 mm Deep
Grinding Machines Coolant
Some Grinding Wheels Feature a
Diamond-Tipped Blade

6. Classification of grinding:
1.Non-percision
2.Percision
 According to produce and
Purpose.

7. Grinding wheel:
 common grinding wheel by using the grain vibration method.
workpiecesurfaceincrease
Height decrease

8. Definition:
A grinding wheel is a Multitooth cutter made up of many hard
Particles known as abrasive which have been crushed to leave
sharped edges for machining.

9. Types of grindingwheel:

10.  Removal of stocks
 Generation Of Cylindrical, flat and curved surface
 Cutting of operation
 Production of sharp edges and points
Basic function of grinding wheel

12.  There are two ways Produce nanoparticles. With the
condensation or "bottom-up" method, the particles are created
through molecular aggregation of an existing substance in
dissolved, liquid, or gaseous form.
 These sol-gel techniques, precipitation techniques, micro-
emulsion and gas phase processes are advantageous in that it is
possible to produce high-purity, practically mono-dispersed
spherical particle systems.
 The production of very fine particles through comminution of
coarse particles is referred to as the dispersion or "top-down"
method.
 High energy densities such as those achieved in agitator bead
mills are required for such grinding tasks.
 Wet grinding is the primary mode of operation for agitator
bead mills. They are employed in many branches of industry
for comminution of raw materials as well as dispersing fine
pigments and products of the "bottom-up" method
 nds for "Multilayer Ceramic Capacitor". As chip capacitors for

13. Grinding machine

14. High ball milling:
 Ball milling process where a powder mixture placed in the ball mill
is subjected to high-energy collision from the balls.
 This process was developed by Benjamin and his coworkers at the
International Nickel Company in the late of 1960.
 It was found that this method, termed mechanical alloying, could
successfully produce fine, uniform dispersions of oxide particles
(Al2O3, Y2O3, ThO2) in nickel-base superalloys that could not be
made by more conventional powder metallurgy methods.

15.  Besides materials synthesis, high-energy ball milling is a
way of modifying the conditions in which chemical
reactions usually take place either by changing the
reactivity of as-milled solids (mechanical activation —
increasing reaction rates, lowering reaction
temperature of the ground powders)—or by inducing
chemical reactions during milling (mechanochemistry).
 particles have all the same chemical composition:
amorphization or polymorphic transformations of
compounds, disordering of ordered alloys, etc.

16. Process in ball milling:
 The alloying process can be carried out using different apparatus,
namely, attritor, planetary mill or a horizontal ball mill.
 However, the principles of these operations are same for all the
techniques. Since the powders are cold welded and fractured
during mechanical alloying, it is critical to establish a balance
between the two processes in order to alloy successfully.
 Planetary ball mill is a most frequently used system for mechanical
alloying since only a very small amount of powder is required.
 Therefore, the system is particularly suitable for research purpose
in the laboratory.
 The ball mill system consists of one turn disc (turn table) and two
or four bowls.
 The turn disc rotates in one direction while the bowls rotate in the
opposite direction.

17. The rotation directions of the
bowl and turn disc are opposite,
the centrifugal forces are
alternately synchronized.
Thus friction resulted from the
hardened milling balls and the
powder mixture being ground
alternately rolling on the inner
wall of the bowl and striking the
opposite wall.
The impact energy of the milling
balls in the normal direction
attains a value of up to 40 times
higher than that due to
gravitational acceleration.
Hence, the planetary ball mill can
be used for high-speed milling.

18. During the high-energy ball milling process, the powder particles are
subjected to high energetic impact.
 The mechanical alloying process can be divided into
four stages:
(a) initial stage,
(b) intermediate stage,
(c) final stage, and
(d) completion stage.

19.  At the initial stage of ball milling
The powder particles are flattened by the compressive forces
due to the collision of the balls. Micro-forging leads to changes in the shapes of
individual particles, or cluster of particles being impacted repeatedly by the
milling balls with high kinetic energy. However, such deformation of the powders
shows no net change in mass.
 At the intermediate stage of the mechanical
The intimate mixture of the powder constituents decreases
the diffusion distance to the micrometer range. Fracturing and cold welding are
the dominant milling processes at this stage. Although some dissolution may take
place, the chemical composition of the alloyed powder is still not homogeneous.

20.  At the final stage :
Refinement and reduction in particle size is evident. The
microstructure of the particle also appears to be more homogenous in
microscopic scale than those at the initial and intermediate stages. True alloys
may have already been formed.
 At the completion stage
The powder particles possess an extremely deformed
metastable structure. At this stage, the lamellae are no longer resolvable by
optical microscopy. Further mechanical alloying beyond this stage cannot
physically improve the dispersoid distribution.

23. Applications:
 Ball mills are used for grinding materials such as coal, pigments, and
feldspar for pottery.
 Grinding can be carried out wet or dry, but the former is performed at
low speed. Blending of explosives is an example of an application for
rubber balls.
 For systems with multiple components, ball milling has been shown to be
effective in increasing solid-state chemical reactivity.
 Additionally, ball milling has been shown effective for production of
amorphous materials.

24. Advantage:
 Ball milling boasts several advantages over other systems:
 The cost of installation and grinding medium is low;
 The capacity and fineness can be adjusted by adjusting the diameter of the
ball;
 It is suitable for both batch and continuous operation;
 It is suitable for open and closed-circuit grinding;
 It is applicable for materials of all degrees of hardness.