Summary of the invention
The technical problems to be solved by the present invention are: providing a kind of ceramic matric composite oxidation environment carbon interface consumer
Product determine method, solve it is of the existing technology can not Accurate Prediction go out unidirectional SiC/SiC composite material in oxidation environment
Under interface consumer integrate cloth the problem of.
The present invention uses following technical scheme to solve above-mentioned technical problem:
A kind of ceramic matric composite oxidation environment carbon interface consumption volume determines method, includes the following steps:
Step 1, the volume and quality of ceramic matric composite are obtained, and the density of material is calculated;
Step 2, the total radical of fiber is counted in the cross section of machine direction according to material, calculates the average thickness at carbon interface
And average fibre diameter;
Step 3, according to whether contact with each other between the fiber on material cross-section and contact point number, by material cross
Fiber on section is divided into individual fibers, single-contact fiber, two-point contact fiber and Multi-contact fiber, and counts respective class
The number of fiber type;
Step 4, between the average thickness, average fibre diameter and fiber based on carbon interface contact point number, calculate
The area at carbon interface on the outside of each type fiber, and further calculate the carbon mass fraction that material contains;
Step 5, the matrix cracking number a of outer surface, the distance between measurement adjacent base crackle and material are obtained
Material at a distance from two cross sections of machine direction are between premature crackle, total a+1 distance, by above-mentioned distance from it is small to
Big sequence, using minimum range as the 1st distance, maximum distance is as the a+1 distance;
Step 6, it is based on oxidation kinetics equation, calculates the carbon interface consumption length r that material is inscribed in different oxidationsc;
Step 7, carbon interface is consumed into length rcAcquire distance with step 5 1/2 is compared: working as rc< minimum range/2
When, it is l that carbon interface, which consumes total length,c_c=(2a+2) rc;Work as rcWhen >=maximum distance/2, carbon interface consumes total length lc_cFor step
The rapid 5 all sum of the distance acquired;Work as rcIn certain two distance 1/2 between when, i.e.,X=1 ..., a, lc_c(2a+2-2x) is added equal to the 1st to x-th sum of the distance
rc;
Step 8, total length is consumed based on the gross area at carbon interface on material cross-section and carbon interface, material oxygen is calculated
Carbon interface consumption volume and its regularity of distribution during change.
As a preferred solution of the present invention, the average thickness at carbon interface described in step 2, calculation formula are as follows:
Wherein, e is the average thickness at carbon interface, and n is the total radical of fiber, eiExpression randomly selects the 1/ of the total radical of fiber
The carbon interfacial thickness of i-th fiber peripheral in 100.
As a preferred solution of the present invention, average fibre diameter described in step 2, calculation formula are as follows:
Wherein, dfFor average fibre diameter, n is the total radical of fiber, dfiIt indicates to randomly select in the 1/100 of the total radical of fiber
The diameter of i-th fiber.
As a preferred solution of the present invention, on the outside of fiber described in step 4 carbon interface area, calculation formula are as follows:
Wherein, ScjThere are the area at carbon interface on the outside of the fiber of j contact point between other fibers, j=0,1 ...,
The number of q, q the Maximum Contact point between fiber, rfFor fiber mean radius, e is the average thickness at carbon interface.
As a preferred solution of the present invention, carbon interface described in step 6 consumes length rc, calculation formula are as follows:
Wherein, k0For the Oxidation Rate Constants of Antioxidants at carbon interface, EaFor the oxidation reaction activation energy at carbon interface, R is general gas
Body constant, T are environment temperature,For the oxygen partial pressure in environment, McFor the molal weight at carbon interface, ρcFor the close of carbon interface
Degree, t is oxidation time.
The invention adopts the above technical scheme compared with prior art, has following technical effect that
1, the present invention considers actual distribution of the fiber in unidirectional SiC/SiC composite material to the shadow of carbon interface content
It rings, while considering oxygen and enter from material perpendicular to two endfaces of fiber and the oxidation at carbon interface, oxygen are split from matrix
Enter oxidation to material internal interface at line, can accurately provide material oxidation after a certain period of time carbon interface consumption volume and
Its distribution situation.
2, the whole process that the present invention calculates is succinctly efficient, overcomes the shortcomings that experimental method is at high cost, time-consuming.
Specific embodiment
Embodiments of the present invention are described below in detail, the example of the embodiment is shown in the accompanying drawings.Below by
The embodiment being described with reference to the drawings is exemplary, and for explaining only the invention, and is not construed as limiting the claims.
A kind of unidirectional SiC/SiC composite material oxidation environment interface consumption volume of the present invention determines method, including walks as follows
It is rapid:
(1) unidirectional SiC/SiC composite sample is polishing to smooth in two sections of machine direction, and measures material
Size in all directions calculates the volume of material, and using the quality of high-precision mass sensor measurement material;
Unidirectional SiC/SiC composite sample is rectangular parallelepiped structure, and length, width and height are respectively l, w, h, then the volume of material
Vcomp=l*w*h.
(2) material after polishing is put into scanning electron microscope (SEM), material cross-section is shot, counted
The total radical of fiber measures average value, the average fibre diameter of interfacial thickness;
The total radical n of fiber to the fiber circular section in material section by being counted to obtain;
Interface average thickness e is 1/100 by randomly selecting the total radical n of fiber, to the boundary layer of these fiber peripherals
Thickness measures, and is then averaged to obtain, it may be assumed that
In formula, eiIndicate the interfacial layer thickness of i-th fiber peripheral.
Average fibre diameter dfAnd 1/100 by randomly selecting the total radical n of fiber, the diameter of these fibers is carried out
Measurement, is then averaged to obtain, it may be assumed that
In formula, dfiIndicate the diameter of i-th fiber.
Outer surface matrix micro-cracks number a counts to obtain by shooting cuboid surface of test piece, matrix cracking spacing
lc, the distance between two end faces of material and premature crackle dcTape measure is carried by SEM to obtain.
(3) according to whether contacting with each other between fiber in material cross-section SEM photograph and the number of contact point, by material
Fiber on cross section is divided into individual fibers, single-contact fiber, two-point contact fiber and Multi-contact fiber, and counts corresponding
The number of types of fibers;
The number q of Maximum Contact point between fiber is counted by material section SEM photograph first, is then determined fine with other
There is no the fiber number v of contact point between dimension0, there are the fiber of 1 contact point (single-contact fiber) number v1, with other fibres
There are the fiber of 2 contact points (two-point contact fiber) number v between dimension2, there are the fibres of q contact point between other fibers
Tie up (two-point contact fiber) number vq, then have:
N=v0+v1+v2+...+vq (3)
(4) between average thickness and fiber based on interface contact point number, calculate every kind of fiber on the outside of carbon interface
Area, and further calculate the carbon mass fraction that material contains;
The area S at individual fibers outer surface carbon interfacec0Are as follows:
Sc0=π [(rf+e)2-rf 2] (4)
In formula, rfIndicate fiber mean radius.
There are the area S at the fibrous outer surfaces carbon interface of j contact point between other fiberscjAre as follows:
Then gross area S in interface on material cross-sectioncAre as follows:
Sc=v0Sc0+v1Sc1+...+vjScj+...+vqScq (6)
In formula, ScqThere are the carbon interfacial areas of the fibrous outer surfaces of q contact point between other fibers.
The mass fraction ω at carbon interfacecIt may be expressed as:
In formula, ρcIndicate the density at carbon interface, ρcompIndicate the density of composite material, VfIndicate fiber volume fraction, it can
To pass through area S shared by fiber on measurement material cross-section SEM photographfIt calculates:
(5) obtain outer surface matrix micro-cracks number and between spacing, two end faces of one step surveying material of going forward side by side
The distance between premature crackle, by the distance between matrix cracking spacing, two end faces of material and premature crackle
It sorts from small to large;
Matrix cracking number is a, matrix cracking spacing lc, the distance between two end faces of material and premature crackle dc,
Then have:
lc1+lc2+...+lca-1+dc1+dca=l (9)
In formula, lc1Indicate number first spacing between Article 2 matrix cracking from left to right, lca-1It indicates from left past
Right several the a-1 articles spacing between a articles matrix cracking, dc1It indicates between material left end face and first matrix cracking
Distance, dcaIndicate the distance between a articles matrix cracking and material right end face.
(6) it is based on oxidation kinetics equation, calculates the interface consumption length that material is inscribed in different oxidations;
Interface consumes length rcAre as follows:
In formula, k0It is the Oxidation Rate Constants of Antioxidants at carbon interface, EaIt is the oxidation reaction activation energy at carbon interface, R is general
Gas constant, T are environment temperatures,It is the oxygen partial pressure in environment, McIt is the molal weight at carbon interface, when t is oxidation reaction
Between.
(7) compare the interface consumption length and matrix cracking spacing that are calculated 1/2, two end faces of material and neighbouring base
1/2 size relation of distance between body crackle, will sort from small to large between them;If interface, which consumes length, is more than or equal to base
The 1/2 of body crack spacing, then consumption length in interface is equal to the 1/2 of matrix cracking spacing, and as the growth of time no longer changes;
If interface consumes 1/2 that length is less than matrix cracking spacing, interface consumes length and is equal to calculated value, and with the growth of time
And increase;Similarly, if the interface consumption length being calculated is more than or equal between two end faces of material and premature crackle
The 1/2 of distance, then interface consumption length be equal between two end faces of material and premature crackle distance 1/2, and with when
Between growth no longer change;If the interface consumption length being calculated is less than the spacing of material two end faces and premature crackle
From 1/2, then consumption length in interface is equal to calculated value, and increases with the growth of time;
(8) based on interface cross-sectional area and consumption length, be calculated the interface consumption volume during material oxidation and
Its regularity of distribution;
Interface consumes volume VCIt may be expressed as:
VC=nlc_cSc (11)
In formula, lc_cThe total length consumed for carbon interface around single fiber.
For the unidirectional SiC/C/SiC composite material in 700 DEG C, 100KPa pure oxygen environment, it is calculated not
With oxidation moment carbon interface consumption volume and its distribution situation.
(1) unidirectional SiC/SiC composite sample is polishing to smooth in two sections of machine direction, and measures material
Size in all directions is respectively l=13mm, w=3mm, h=3mm, as shown in Figure 1, calculating the volume V of materialcomp
=l*w*h=117mm3, the quality m of material is obtained using high-precision mass sensor measurementcompFor 0.29835g;
(2) material after polishing is put into scanning electron microscope (SEM), material cross-section is shot, counted
The total radical of fiber be n=24570, randomly select 245 fibers, measure its ambient interfaces thickness average value be e=0.1 μm,
Average fibre diameter is df=14 μm;
(3) in the present embodiment, fiber volume fraction VfIt may be expressed as:
In the present embodiment, the density p of materialcompIt may be expressed as:
(3) according to whether contacting with each other between fiber in material cross-section SEM photograph and the number of contact point, by material
Fiber on cross section is divided into individual fibers, single-contact fiber, two-point contact fiber and Multi-contact fiber, as shown in Fig. 2,
Wherein individual fibers be 3292, single-contact fiber 7567, two-point contact fiber 5848, three point contact fiber 3882
Root, four point contact fibers 2359, five point contact fibers 1278, six point contact fibers 344;
(4) between average thickness and fiber based on interface contact point number, calculate every kind of fiber on the outside of carbon interface
Area, and further calculate the carbon mass fraction that material contains;
In the present embodiment, the area S at individual fibers outer surface carbon interfacec0Are as follows:
Sc0=π [(rf+e)2-rf 2]=4.4274 μm2 (14)
Therefore, the area S at all individual fibers outer surface carbon interfacesc_indAre as follows:
Sc_ind=3292 × 4.4274=14575.0008um2 (15)
In the present embodiment, the area S at single-contact fibrous outer surfaces carbon interfacec1Are as follows:
In formula,As shown in figure 3, therefore, Sc1=4.3090 μm2, outside all single-contact fibers
The area S at surface carbon interfacec_1Are as follows:
Sc_1=7567 × 4.3090=32606.203 μm2 (17)
Similarly, the area S at two-point contact fibrous outer surfaces carbon interfacec2Are as follows:
Therefore, Sc2=4.1906 μm2, the area S at all two-point contact fibrous outer surfaces carbon interfacesc_2Are as follows:
Sc_2=5848 × 4.1906=24506.6288 μm2 (19)
Similarly, the area S at three point contact fibrous outer surfaces carbon interfacec3=4.0722 μm2, outside all two-point contact fibers
The area S at surface carbon interfacec_3Are as follows:
Sc_3=3882 × 4.0722=15808.2804 μm2 (20)
Similarly, the area S at four point contact fibrous outer surfaces carbon interfacesc4=3.9538 μm2, outside all four point contacts fibers
The area S at surface carbon interfacec_4Are as follows:
Sc_4=2359 × 3.9538=9327.0142 μm2 (21)
Similarly, the area S at five point contact fibrous outer surfaces carbon interfacesc5=3.8354 μm2, outside all five point contacts fibers
The area S at surface carbon interfacec_5Are as follows:
Sc_5=1278 × 3.8354=4901.6412 μm2 (22)
Similarly, the area S at six point contact fibrous outer surfaces carbon interfacesc6=3.717 μm2, outside all five point contacts fibers
The area S at surface carbon interfacec_6Are as follows:
Sc_6=344 × 3.717=1278.648 μm2 (23)
Therefore, the gross area S at carbon interfacecIt may be expressed as:
Sc=Sc_ind+Sc_1+Sc_2+...+Sc_6=0.103mm2 (24)
In the present embodiment, the mass fraction ω of carboncIt may be expressed as:
(5) obtaining the initial micro-crack number of outer surface matrix is a=3, and matrix cracking is sorted from left to right, matrix
Crack spacing is respectively lc1=7mm, lc2=3mm, go forward side by side between two end faces of one step surveying material and premature crackle away from
From respectively dc1=2mm, dc3=1mm, as shown in Figure 1, by matrix cracking spacing, two end faces of material and premature crackle
The distance between sort from small to large;
In the present embodiment, two end faces of the spacing between 3 matrix crackings and material and premature crackle it
Between distance-taxis are as follows:
dc3< dc1< lc2< lc1 (26)
(6) it is based on oxidation kinetics equation, calculates the interface consumption length that material is inscribed in different oxidations;
In the present embodiment, k0It is the Oxidation Rate Constants of Antioxidants at carbon interface, k0=1070, EaIt is the oxidation at carbon interface
Reaction activity, Ea=123000J/mol, R are universal gas constants, and R=8.3145J/mol.K, T are environment temperature, T=
973.15KIt is the oxygen partial pressure in environment,McIt is the molal weight at carbon interface, Mc=12g/mol, t
It is oxidation time, interface consumes length rcAre as follows:
(7) compare the interface consumption length and matrix cracking spacing that are calculated 1/2, two end faces of material and neighbouring base
1/2 size relation of distance between body crackle, will sort from small to large between them;If interface, which consumes length, is more than or equal to base
The 1/2 of body crack spacing, then consumption length in interface is equal to the 1/2 of matrix cracking spacing, and as the growth of time no longer changes;
If interface consumes 1/2 that length is less than matrix cracking spacing, interface consumes length and is equal to calculated value, and with the growth of time
And increase;Similarly, if the interface consumption length being calculated is more than or equal between two end faces of material and premature crackle
The 1/2 of distance, then interface consumption length be equal between two end faces of material and premature crackle distance 1/2, and with when
Between growth no longer change;If the interface consumption length being calculated is less than the spacing of material two end faces and premature crackle
From 1/2, then consumption length in interface is equal to calculated value, and increases with the growth of time;
In the present embodiment, length r is consumed for interfacecWith matrix cracking spacing lc, two end faces of material and neighbouring base
Distance d between body cracklecBetween judgement process, as shown in figure 4, wherein around single fiber carbon interface consume total length table
It is shown as lc_c。
(8) based on interface cross-sectional area and consumption length, be calculated the interface consumption volume during material oxidation and
Its regularity of distribution.
In the present embodiment, length r is consumed according to interface under different momentscWith matrix cracking spacing lc, material two end
Distance d between face and premature cracklecBetween size relation, can judge single fiber ambient interfaces consumption volume
Distribution, is illustrated, as shown in (a) of Fig. 5, (b), (c), (d), (e) herein by taking individual fibers as an example.
In the present embodiment, the consumption volume changing rule at carbon interface is characterized with the mass loss rate of material, Fig. 6 is aobvious
Show that the mass loss rate of unidirectional SiC/SiC composite material changes over time curve, matrix cracking model is not considered by comparison
With the more matrix cracking models of consideration, it can be seen that the knot of the prediction model simulation proposed by the present invention for considering more matrix crackings distributions
Fruit and experimental test result are coincide preferable.
The above examples only illustrate the technical idea of the present invention, and this does not limit the scope of protection of the present invention, all
According to the technical idea provided by the invention, any changes made on the basis of the technical scheme each falls within the scope of the present invention
Within.