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in hypersonic coating , the coating impact formed by solid particle impact as compared to other processes  is which coating formed by molten or semi molten particles.

bonding temprature increase with increasing melting point of material

the material with melting point less than 1500 0c have critical bonding temprature less than room temprature, this make ceramic material which has melting temprature less than 15  00 0c bonded  .

with spray particles 40 %melting degree coating with porosity 70% can be obtained

 

Task3：讲座二：2. Landau theory of martensitic and ferroelastic phase transitions-Ekhard Salje

cordierite have small thermal expansions. ceramics are good insulators

all hitech material other than silicon are made up of  perovskite

lecture 2

introduction to mterial sciences, landau theory  of martensitic and ferroelastic phase transition

the local hamiltonian

 2

interfaces melts first

memory element of one nanometer square,

       

LECTURE 1

LOW TEMP MATERIAL

C60 is 0D

CNT is 1D

GRAPHENE/GRAPHITE 2/3D

3D BULK

2D QUANTUM WALL

1D QUANTUM WIRE

​​​​​​​ QUANTUM DOT

​​​​​​​DIMENSION REDUCTION FROM 3D TO 2D THIS QUANTUM PHENOMENA CAN BE USED IN FUTURE ELECTRONICS.

​​​​​​​FOR EXAMPLE, IN QUANTUM DOT ELECTRONS ARE CONFINED IN 3D BUT Q.DOT HAS 0 D.

​​​​​​​CVD IS EASY TO LEARN TWO PERAMETERS, TEMPERATURE, CARRIER GASES I.E INERT GASES. THIS METHOD USED FOR ALL DIMENTIONAL QUANTUM MATERIALS.

MOLECULAR BEAM EPITAXY

​​​​​​​SOPHISTICATD AND IMP DUE TO CLEAN ENVRONMENT,I.E VACCUME, CONTRIOL ELEMENT, SUBSTRATE TEMP AND LAYERS. 

​​​​​​​TYPICAL LAYER METHOD

IF SUBSTRATE HAVE DIFF LATICE CONSTANT THEN ISLAND GROWTH (VOLMER-WEBER) SOME SMALL 3D PARTICLES ARE ISLAND/

IF LATICE CONSTANT MATCHED :LAYER BY LAYER GROWTH (FRANK=VAN DER MERWE)  MATERIAL DIFFUSE 

​​​​​​​STRANSKI KARAANOV (MIXED GROWTH)

​​​​​​​INITIAL LAYER BY LAYER THEN 2D MIXTURE SOME AREA FROM FILMS OF THIN LAYER AND SOME AREA PALSTER, HOW TO CONTROL; CLEAN SURFACE AND CONTROL ENERGY
HOW TO CONTROL ENERGY: TO CONTROL SUBSTRATE TEMPRATURE: LARGE RANGE TO REDUCE TEMP TO SOME LOW  DIFFUSING SMALL PARTICLE STICKS ON SURFSACE  OR GET IT OUT TO TO COOL DOWN UPTO 1000 K.   

WHY ULTRA HIGH VACCUME IMP

​​​​​​​AMOUNT OF MATERIAL IS SO SMALL THAT WE DONT NEED ANY CONTAMINATION. 10 POWER -6 IS NOT NECESSARY WE NEED 10 POWER -8 TORR..NOTHING CAN GO INSIDE CHAMBER EXCEPT SMALL MOLECULES OF HYDROGEN GAS, BUT ITS RANGE IS VERY SMALL IF WE PUMP INSIDE WE CAN GET RID OF H MOLECULE ETC

​​​​​​​ROTARY PUMP: BOTH HAVE MECHENICAL PARTS TO CREAT VACCUME

​​​​​​​ION PUP WITHOUT NOISE, POWERFULL AND QUITE PUMP

​​​​​​​TITANIUM SIBLIMATION PUMP, TO CREAT VACCUME IN SHORT TIME.

RESIDUAL GAS ON THE WALL WHICH CAN COOL DOWN CHAMBER ALSO

​​​​​​​CHARACTERIZATION

​​​​​​​SEM ,

EDS, CHEMICAL INFO,OXYGEN SUBSTRATE, C FROM CONTAMINATION,DISTRIBUTION OF ELEMENTS

AFM ​​​​​​​: TELL MORE INFO ABOUT THICKNESS, MOS2 SAMPLE HEIGHT IS 4NM SO 2D MATERIAL

ELECTRON GUM:

​​​​​​​TUNG WIRE, LaB6 SINGLE CRYSTAL OR NEEDLE LIKE TUNGSTON WIRE   

​​​​​​​TEM CAN T5ELL PROFILE OF MATERAL:

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​​​​​​​SCANNING PROBE MICROSCOPY:SPM

​​​​​​​INVENTED BY BINNIG ND ROHRER 1981,GET NOBEL PRIZE 1986. USING  PHYSICAL PROBE OR NEEDLE

IT FORMS IMAGES OF SURFACE AS SEM: information about the surface topography and composition of the sample AND TEM:A TEM has many uses. Its main purpose is  to create high magnification images of the internal structure of a sample . This can be used to gather information on crystalline structures, stress, internal fractures, contamination, and more

HOW STM WOK

HARD MATERIL TIP OF PROBE, TUNGSTEN TIP , BECAUDSE OF NOT ACHIEVING FULLY ULTRA HIGH VACCUME ALWAYS RESIDUAL GASES ABSORBED SUCH ASOXYGEN, CO OR OH GROUP.

 

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