CN1145344A - Method of using self-spreading high temp synthesis for prepn. of foamed ceramic materials - Google Patents

Abstract

A self-spreading high-temp synthesis (SHS) process for preparing foam ceramic materials includes such technological steps as adding stoichiometric two or more powdered reactants to grout which is able to generate patial liquid phase after reaction, additive, water glass and carboxymethyl cellulose, impregnation, baking and sintering, and features short sintering period, no need of high-temp sinter furnace, high refractory (higher than (800 deg.C) nature and low cost.

Description

Method for preparing foam ceramic material by utilizing self-propagating high-temperature synthesis

The invention relates to preparation of a foam ceramic material, and belongs to the field of materials.

The foamed ceramic has good high temperature resistance, developed surface and high activity, and can be widely used in the industrial fields of metal melt purification, internal combustion engine tail gas filtration, chemical catalyst carriers and the like. The important method for preparing the foamed ceramic material in the prior art is to immerse the polyurethane foamed plastic serving as a precursor material into ceramic slurry, take out the ceramic slurry, extrude redundant slurry, dry the ceramic slurry and sinter the ceramic slurry at high temperature for a long time. In recent years, the technology of preparing the foamed ceramic material by the electric pulse pressure sintering method is also utilized. These methods are unsatisfactory in terms of process cycle, cost, performance, etc. At present, foamed ceramic materials (such as mullite, A) prepared in Chinal₂O₃Etc.), the filtering materials (such as SiC, cordierite, etc.) applied in the aspect of high-temperature metal melt purification, besides being successfully used in the fields of non-ferrous metals and alloys thereof, have not completely reached the degree of practicality, but have not been mature in material selection and preparation process in the important field of internal combustion engine exhaust filtration. Therefore, the research on the foamed ceramic material is a leading issue of research and investigation by material scientists.

The chinese patent office 1992, month 10 and 14, discloses a patent application entitled "ceramic foam material filter and method of making the same," which is filed under the number 92102883.0. The main component of the material is Al₂O₃、SiO₂Or with addition of part of ZrO₂The process is realized by four steps of slurry preparation, impregnation, drying and sintering. In the preparation of the slurry, Al is selected₂O₃、SiO₂Or with addition of part of ZrO₂Then, Y is added₂O₃(1-5%) and a binder, adding water in an amount of 25-35% by weight, and stirring to form slurry, wherein thebinder is bentonite 2-5%, carboxymethyl cellulose 1-3% and phosphoric acid 3-6% (or α -starch 1-2%) in the total weight, and the binder has the functions of keeping high strength in low temperature and medium temperature processes before sintering a blank, and Y is Y₂O₃The porous foamed plastic is soaked in the slurry, the redundant slurry is extruded, then the green body adhered with the mixture slurry is heated to 200-300 ℃ to be dried, and finally the green body is sintered for 1-6 hours at the high temperature of 1500-1650 ℃ to be solidified, the refractoriness of the material is 1650-1800 ℃, but the material has the following defects of long production period of ①, high cost, low compression strength at ② high temperature and low thermal shock resistance.

In order to overcome the defects in the prior art and prepare the foamed ceramic material with short production period, simple process method, low cost, refractoriness of more than 1800 ℃ and good high-temperature performance, the technical proposal of the invention is provided.

The basic idea of the invention is that the process of forming the dense foamed ceramic material is a highly exothermic chemistryThe principle of the reaction process is that a Self-propagating High-temperature synthesis (SHS, the same applies below) method is utilized to induce a chemical reaction to occur locally in a system under the premise of providing necessary energy (a certain temperature) for the system, and then the chemical reaction process is continued under the support of Self-released High heat, and finally, a combustion (reaction) wave is propagated to the whole system, so that the required ceramic material is prepared. In order to achieve this concept, two or more substances must be selected that are capable of undergoing the SHS reaction and producing a partial amount of liquid phase, thermodynamically, depending on the thermal effect (in Δ H °)of their reaction at 25 ℃₂₉₈Expressed as Tad) and the amount of liquid phase (theoretical value, θ) generated after the reaction were calculated₀Expressed in terms of θ) is added to the system by controlling the type and amount of the additive in the system, and the amount of the liquid phase to be designed (control value)₁Or theta_1CExpressed), design preheat temperature (calculated for the test, in terms of T)₀Or T_0CExpressed) and the actual firing temperature (in T) of the green body sintering_KShown), the SHS method is used for preparing the foamed ceramic material.

The invention discloses a method for preparing a foamed ceramic material by utilizing self-propagating high-temperature synthesis, which comprises the step of preparing slurry [1]]Dipping [2]]And drying [3]And sintering [4]]The process is characterized in that: the preparation of the slurry comprises adding two or more than two of which the particle size is larger than 200 meshes according to the stoichiometric weight, and the slurry can perform SHS reaction and generate partial liquid phasor (a theoretical calculation value theta)₀) The reactant powder of (3); comprises 1-40 wt% of additive (the same applies below) based on the total weight of reactants; comprises water glass accounting for 2-5% of the total weight of reactants; comprises carboxymethyl cellulose accounting for 0.2-3.0% of the total weight of reactants; comprising water accounting for 50-100% of the total weight of all the added materials; adding water into the materials, and uniformly stirring to obtain slurry; sintering [4]]The process is completed by utilizing a self-propagating high-temperature synthesis (namely SHS) method; controlled amount of liquid phase (θ) in the system during the completed SHS reaction₁Or theta_1C) 40-80%; the actual ignition temperature for sintering the green body by using the SHS reaction is T_K。

The invention is designedThe method for preparing the foamed ceramic material by utilizing the self-propagating high-temperature synthesis is further characterized in that the additives added in the ingredients are high-melting-point metal powder and ceramic powder, the commonly used high-melting-point metal powder comprises Ti, Cr, Zr, Mo and W, and the ceramic powder comprises Al₂O₃、SiO₂、ZrO₂And SiC; designed preheating temperature T of blank₀Upper and lower limits or minimum preheat design temperature T_0CAll of which ensure that 40-80% of the liquid phase amount theta exists in the system during the SHS reaction₁Or theta_1COn the premise of obtaining the product through thermodynamic calculation; controlling the liquid phase amount theta of 40-80% in the system during SHS reaction of the blank₁Or theta_1CIs a theoretical calculation of theta based on the liquid phase quantity₀And the types and the amount of the additives are controlled and determined by thermodynamic calculation and experiments; when selecting different additives and different addition amounts, if θ₀If<40%, theta should be controlled₁In the range of 40-60% to calculate T₀Or T_0CIf theta is greater than theta₀In the range of 40-60%, theta should be controlled₁In the range of 50-70% to calculate T₀Or T_0CIf theta is greater than theta₀If>60%, theta should be controlled₁In the range of 60-80% to calculate T₀Or T_0C(ii) a Actual ignition temperature T for the blank by means of the SHS reaction_KThe value taking method comprises the following steps: when the preheating temperature T is designed₀Continuously varied over a range, and theta₁T is continuously changed within a range of 40-80%_KGet T₀When the preheating temperature T is designed₀Continuously varied over a range, and theta₁Is a stable fixed value (called theta)_1C)When, T_KShould be taken to reach this fixed value (θ)_1C) Minimum design preheat temperature (called T)_0C) Then adding 300-400 ℃.

The key point of the invention is that the actual ignition temperature T of the blank for the SHS reaction is determined on the premise that the addition amount under the specified condition is satisfied, so that the addition amount reaches the specified liquid phase amount in the SHS reaction_K. Is composed ofThus, for T_KThe determination of (a) is explicitly made as follows:

① first, the theoretical adiabatic temperature (T) at 25 ℃ for the SHS reaction was calculated using the thermodynamic equilibrium equation_ad) And the resulting partial theoretical liquid phase quantity (. theta.)₀)，

② secondly, by adding 1-40% of additive, the liquid phase amount (theta) after reaction is controlled to be regulated₁40-80%) of the blank, and calculating the designed preheating temperature T of the blank by using a thermodynamic equilibrium equation₀Or T_0C，

③ finally, the preheating temperature T is designed according to the blank₀Or T_0CDetermining the actual ignition temperature T of the final blank during the SHS reaction_K。

The specific SHS reaction will now be described:

the principle of calculation using the thermodynamic equilibrium equation is that, assuming that the reaction takes place under adiabatic conditions and 100% of the reactants undergo the stoichiometric exothermic SHS reaction, the heat evolved is Δ H °₂₉₈All used to heat the product, then, if the reactionoccurs at 25 ℃, there are: - Δ H °₂₉₈＝∑n_i(H°_Tad-H°₂₉₈)_{i products}In the formula (H degree)_Tad-H°₂₉₈) As the relative enthalpy of mass mol n_iBy mol of product

ΔH°₂₉₈-reaction thermal effect (Normal temperature 25 ℃ C.)

The physical meaning of the above formula is: the heat effect (or enthalpy change) of the SHS reaction (i.e., highly exothermic chemical reaction) causes the product to rise to Tad, i.e., the total amount of enthalpy change that the product rises from 25 ℃ to the adiabatic temperature Tad equals the heat effect of the reaction.

If, the reactants are preheated to T₀Or T_0CTemperature, remixing and reacting to obtain:

the essence of the above formula lies in that in order to apply the thermal effect (Δ H °) of the reaction at room temperature₂₉₈) Conveniently calculated, T of the reactants reached by preheating according to Gauss's law₀When the temperature is reduced to 298K, the heat emitted is equal to the heat absorbed by the heatExpressed, due to the assumed adiabatic process, the heat and thermal effect Δ H °₂₉₈All is absorbed by the product, thereby increasing the temperature of the product. When additives are added and preheated to T₀At temperature, the reaction equilibrium equation becomes:

with this calculation, the adiabatic temperature T of the SHS reaction_adAnd amount of liquid phase theta₀Closely related to the reaction heat effect and the product melting point, the substance A and the substance B react with each other to generate a substance AB, and the reaction formula is as follows: a + B→ AB for example, if the melting point of AB is T_m(AB)Latent heat of fusion of Δ H_m(AB)Then T is_adAnd theta₀There are three cases of calculation:

in the first case, if:

in the formula C_PS(AB)-AB solid state heat capacity

At this point, the thermal effect is less, the product AB remains solid without melting at the completion of SHS, and the liquid phase content θ₀＝0，T_ad＜T_m(AB)The calculation formula is as follows:

in the second case, if:

specific time, thermal effect (. DELTA.H. °)₂₉₈) On completion of SHS, the product AB partially melts and T_ad＝T_m(AB)The calculation formula is as follows:

the number of AB fusion fractions, i.e. the liquid phase quantity theta, can be determined₀

In a third case, if:

at this point, the thermal effect is large, upon completion of SHS, the product is totally melted, and T_ad＞T_m(AB)The calculation formula is as follows:

in the formula C_PL(AB)-AB liquid heat capacity

The above calculation methods and the control parameters for the respective reaction systems are shown in the attached Table 1.

The calculations of attached table 1 and the determination of the control parameters thereof will now be described in detail with the following two examples ((a) and (B)) in attached table 1:

…………………………………………………………(A)

………………………………(B)

calculating T_adAnd theta₀：

The adiabatic temperature T_adAnd theoretical values for the liquid phase of the product, are data at 25 ℃ without additives.

The second case described above, i.e., T after the SHS reaction, is found by trial calculation for the formula (A)_adEqual to the product TiB₂Melting point of 3193K, TiB₂Partial melting, calculating theta₀The thermodynamic formula of (a) is:

in the formula

Solid state hot melt

Heat of fusion

θ₀——TiB₂Melting part (wt%)

The following calculation results: theta₀＝35％

As to the formula (B), it was experimentally found that Al was generated after the SHS reaction₂O₃Total melting of TiB₂Is in a solid state, and

and it is similar to the aforementioned third case, the amount of liquid phase is made of molten Al₂O₃Can be calculated out, T is calculated_adThe thermodynamic formula of (a) is: $+{\&Integral;}_{T_{\mathrm{tr}}}^{T_{m\left(A{l}_2{O}_3\right)}}5C_{\mathrm{PS}(\mathrm{\&gamma;}-A{l}_2{O}_3)}\mathrm{dT}+5\mathrm{\&Delta;}{H}_{m\left(A{l}_2{O}_3\right)}$ $+{\&Integral;}_{T_{m\left(A{l}_2{O}_3\right)}}^{T_{\mathrm{ad}}}5C_{\mathrm{PL}\left(A{l}_2{O}_3\right)}\mathrm{dT}+{\&Integral;}_{{}_{298}3C_{\mathrm{PS}\left(\mathrm{Ti}{B}_2\right)}\mathrm{dT}}^{T_{\mathrm{ad}}}$

in the formula: c_PS-solid state heat capacity

ΔH_m-heat of fusion

T_tr-phase transition temperature

ΔH_tr-phase change heat

T_mMelting Point

C_PL-liquid heat capacity

The physical meaning of the above formula calculation (process) is: thermal effect of reaction at 25 ℃ (Δ H °)₂₉₈) Making Al in the resultant₂O₃Heating up from 25 deg.C, making solid phase change (α → gamma) to reach melting point, after all melting, continuously heating up to T_adWhile TiB₂Raising thetemperature from 25 ℃ to T_ad。

Through calculation of T_ad＝2465K，Al₂O₃All melted in the reaction, accounting for the total weight of the system $\frac{5W_{A{l}_2{O}_3}}{5W_{A{l}_2{O}_3}+3W_{\mathrm{TiB}}}=70.8\%$

I.e. theta₀＝70.8％

In the formula (I), the compound is shown in the specification,

、W_TiBare respectively Al₂O₃And the mol molecular weight of TiB.

Calculating T₀Or T_0C：

To ensure theta₁When the additive is added in an amount of 40 to 80%, T is calculated₀Or T_0CThe value is obtained.

At this time, the case of adding one or more additives separately or in combination should be considered, and now taking the case of adding metal separately, ceramic material separately and metal and ceramic mixed as examples, the following are calculated respectively:

for formula(A), the liquid phase quantity theta is controlled to ensure the system₁40-60%, melting 100% of the additive in SHS reaction, and partially TiB₂In a molten state, and therefore, reaction T_adIs TiB₂Melting point, i.e. T_ad3193K. At this time, the SHS reaction is carried out at different preheating temperatures, and the liquid phase amount (between 40-60%) is designed to be continuously changed, so that T is calculated for formula (A)₀The method comprises the following steps:

taking the case of adding 5% of metal Cr powder alone,

because of TiB₂The mol molecular weight of (A) is 70, the addition of 5% Cr is 3.5 converted into mol number, that is, 0.673mol Cr is added, and the preheating temperature T is designed₀Reaction, T₀The calculation formula is:

$+{\mathrm{\&theta;}}^{\&prime;}\mathrm{\&Delta;}{H}_{m\left(\mathrm{Ti}{B}_2\right)}+{\&Integral;}_{298}^{\mathrm{Tm}\left(\mathrm{Cr}\right)}0.0673C_{\mathrm{PS}\left(\text{Cr}\right)}\mathrm{dT}+0.0673\mathrm{\&Delta;}{H}_{m\left(\mathrm{Cr}\right)}+{\&Integral;}_{\mathrm{Tm}\left(\mathrm{Cr}\right)}^{T_{\mathrm{ad}}}0.0673C_{\mathrm{PL}\left(\mathrm{Cr}\right)}\mathrm{dT}$

in the formula, C_PS(Ti)、C_PS(B)、C_PS(Cr)、

Respectively being Ti, B, Cr, TiB₂Solid state heat capacity of

C_PL(Cr)Is liquid heat capacity of Cr、ΔH_m(Cr)Respectively is TiB₂Latent heat of fusion of Cr

T_m(Cr)Melting Point of Cr

The meaning of the above formula is: the reactants and additives are from 25 ℃ to T₀The absorbed heat and the reaction heat effect act simultaneously to make the product and additive reach T_adHigh temperature state, at this time, T_ad3193K, Cr is completely melted, TiB₂Partially melted.

The Cr added into the system is liquid in the reaction, TiB₂The fraction of melt is θ', so that to ensure θ₁And (4) calculating the value of theta' as 40 percent: $\frac{0.0673W_{\mathrm{Cr}}+{\mathrm{\&theta;}}^{\&prime;}{W}_{\mathrm{Ti}{B}_2}}{0.0673W_{\mathrm{Cr}}-W_{\mathrm{Ti}{B}_2}}=40\%$ wherein W is_CrIs the mol molecular weight of Cr,θ' was found to be 0.37, that is, 37%.

The known number is calculated by programming or equation solving to obtain T₀Has a lower limit of 480K to ensure theta₁When calculated as above, θ' is 0.58, i.e., 58%, T can be calculated as 60%₀Has an upper limit of 770K.

For formula (A), 15% SiO of the reactant is added separately₂Calculate T for example₀At this time, according to TiB₂Mol molecular weight of (A) SiO is added₂Amount 10.5 in mol fraction 0.175, system T_ad＝3193K，SiO₂The total melting in the reaction, as above, was calculated as: when theta is₁When the total amount of θ is 40%, θ' is 31%, and when θ is equal to₁60% or so, 54% or so, and SiO₂Cristobalite thermodynamic parameters were used. Calculating T₀The formula of (2) is:

$={\&Integral;}_{{}_{298}C_{\mathrm{PS}\left(\mathrm{Ti}{B}_2\right)}\mathrm{dT}+{\mathrm{\&theta;}}^{\&prime;}\mathrm{\&Delta;}{H}_{m\left(\mathrm{Ti}{B}_2\right)}+0.175\&lsqb;{\&Integral;}_{298}^{T_{\mathrm{tr}}\left(\mathrm{Si}{O}_2\right)}{C}_{\mathrm{PS}(\mathrm{\&alpha;}-\mathrm{Si}{O}_2)}\mathrm{dT}}^{T_{\mathrm{ad}}}$ $+\mathrm{\&Delta;}{H}_{\mathrm{tr}}+{\&Integral;}_{T_{\mathrm{tr}}}^{T_{m\left(\mathrm{Si}{O}_2\right)}}{C}_{\mathrm{PS}(\mathrm{\&beta;}-\mathrm{Si}{O}_2)}\mathrm{dT}\&rsqb;+{\&Integral;}_{T_{m\left(\mathrm{Si}{O}_2\right)}}^{T_{\mathrm{ad}}}0.175C_{\mathrm{PL}\left(\mathrm{Si}{O}_2\right)}\mathrm{dT}$

calculated to obtain theta₁When equal to 40%, T₀Has a lower limit of 810K; theta₁When 60%, T₀The upper limit of (2) is 1060K.

For formula (A), when the metal and ceramic powder are added simultaneously, 5% Cr and 10% SiO by weight of the reactants are added₂For example, calculate T₀. At this time, system T_ad3193K, Cr and SiO in the reaction₂Similarly, when θ is 40% or 60%, TiB is calculated as liquid₂The upper and lower limits of the melting fraction theta' were 31% and 54%, and theta can be obtained based on the heat balance calculation like the above₁When equal to 40%, T₀Lower limit value of (2) is 760K, theta₁When 60%, T₀The upper limit value of (1) is 1020K.

Next, the following will describe the case of adding metal, ceramic and metal and ceramic together, respectively, by taking the formula (B) as an example, and obtaining T_0CThe case (1).

Taking the example of adding 10% of metal Zr,

t is obtained when the system is reacted at 25 ℃ without additives_ad＝2465，θ₀70.8 percent. When 10% of Zr in the reactant is added, the reaction is disassembled to a mol number of 0.792, and all Zr is melted to ensure that theta₁60-80%, when the preheating temperature is designed to carry out SHS reaction, the preheating temperature is designed to be increased to make T be increased_ad＞2303K(Al₂O₃Melting point), it can be seen that at T, the design preheat temperature is increased further_adGreater than 2303K to 3193K (TiB)₂Melting point) and the liquid phase is a stable fixed value theta_1CAnd theta_1C＝73.5%, the calculation method is as follows: $\frac{0.792W_{\mathrm{Zr}}+5W_{A{l}_2{O}_3}}{0.792W_{\mathrm{Zr}}+3W_{\mathrm{Ti}{B}_2}+5W_{A{l}_2{O}_3}}=0.735,$

thus, the system only calculates θ_1CMinimum design preheat temperature T at 73.5%_0CAt this time, Al₂O₃All melt, take T_ad＝2303K，T_0CThe calculation formula is as follows: ${\&Integral;}_{{}_{298}\&lsqb;10C_{\mathrm{PS}\left(\mathrm{Al}\right)}+3C_{\mathrm{PS}\left(\mathrm{Ti}{O}_2\right)}+3C_{\mathrm{PS}\left(B_2{O}_3\right)}\&rsqb;\mathrm{dT}+{\&Integral;}_{{}_{298}0.792C_{\mathrm{PS}\left(\mathrm{Zr}\right)}\mathrm{dT}}^{T_{0C}}}^{T_{0C}}$

$+0.792\&lsqb;{\&Integral;}_{298}^{T_{\mathrm{tr}}}{C}_{\mathrm{PS}(\mathrm{\&alpha;}-\mathrm{Zr})}+{\&Integral;}_{T_{\mathrm{tr}}}^{T_m}{C}_{\mathrm{PS}(\mathrm{\&beta;}-\mathrm{Zr})}+\mathrm{\&Delta;}{H}_{\mathrm{tr}}\left(\mathrm{Zr}\right)+\mathrm{\&Delta;}{H}_{m\left(\mathrm{Zr}\right)}\&rsqb;$ $+{\&Integral;}_{T_{m\left(\mathrm{Zr}\right)}}^{T_{\mathrm{ad}}}0.792C_{\mathrm{PL}\left(\mathrm{Zr}\right)}\mathrm{dT}$

this formula does not express Al₂O₃Solid state equals (α → gamma), but has been taken into account when calculating.

Computer T_0C298K, T without thermodynamic data below 298K_0CError is larger when less than 298K, corrected [ squarePrepared from (1)'_0C298K electric calculating T'_adAnd when 10% of Zr is added, T'_ad2396K, minimum design preheat temperature T_0C＝T′_0C-(T′_ad-2303K ═ 205K], minimum design preheat temperature T_0CThe value is 205K, at which time the (fixed) liquid phase quantity θ_1C＝73.5％。

To add 20% Al₂O₃The ceramic powder is exemplified as an example of the ceramic powder,

when the system is additive-free, T_ad＝2465K，θ₀70.8 percent of Al accounting for 20 percent of the reactant is added₂O₃After that, the reaction was carried out at the designed preheating temperature, which was also at T, in a molar number of 1.41_adOver the range of 2303K to 3193K, the liquid phase amount is a stable fixed value, i.e. theta_1C75.7%, therefore, take T_ad2303K, and Al added and generated₂O₃When all the materials are melted, the minimum design preheating temperature T is calculated_0CWhich isThe calculation formula is as follows: ${\&Integral;}_{{}_{298}(5+1.41)C_{\mathrm{PS}\left(A{l}_2{O}_3\right)}\mathrm{dT}+(5+1.41)\mathrm{\&Delta;}{H}_{m\left(A{l}_2{O}_3\right)}+{\&Integral;}_{{}_{298}3C_{\mathrm{PS}\left(\mathrm{Ti}{B}_2\right)}\mathrm{dT}}^{T_{\mathrm{ad}}}}^{T_{\mathrm{ad}}}$

this formula does not express Al₂O₃Solid state phase transitions, but have been taken into account in the calculations.

The minimum design preheating temperature T is obtained by calculation_0CThe value is 726K.

Calculation of the minimum design preheating temperature when adding metal and ceramic powders simultaneously (total addition less than 20%), now 5% Cr and 10% SiO of the total weight of the reactants₂For example, only T is calculated in this case_0C：

Adding 5% Cr, the mol number is 0.692, adding 10% SiO₂Converting into mol number of 1.2, and taking T_ad2303K, all the additives added were melted, and Al was formed at the same time₂O₃Also totally melted,. theta_1C＝74.6％，T_0CThe calculation formula is as follows: ${\&Integral;}_{{}_{298}\&lsqb;10C_{\mathrm{PS}\left(\mathrm{Al}\right)}+3C_{\mathrm{PS}\left({\mathrm{Ti}}_{O}2\right)}+3C_{\mathrm{PS}\left(B_2{O}_3\right)}\&rsqb;\mathrm{dT}+{\&Integral;}_{{}_{298}\&lsqb;0.692C_{\mathrm{PS}\left(\mathrm{Cr}\right)}}^{T_{0C}}}^{T_0}$ ${\&Integral;}_{{}_{298}0.692C_{\mathrm{PS}\left(\mathrm{Cr}\right)}\mathrm{dT}+0.692\mathrm{\&Delta;}{H}_{m\left(\mathrm{Cr}\right)}+{\&Integral;}_{T_{m\left(\mathrm{Cr}\right)}}^{T_{\mathrm{ad}}}0.692C_{\mathrm{PL}\left(\mathrm{Cr}\right)}\mathrm{dT}+}^{T_{m\left(\mathrm{Cr}\right)}}$ ${\&Integral;}_{{}_{298}1.2C_{\mathrm{PS}\left(\mathrm{Si}{O}_2\right)}\mathrm{dT}+1.2\mathrm{\&Delta;}{H}_{m\left(\mathrm{Si}{O}_2\right)}+{\&Integral;}_{{}_{298}1.2C_{\mathrm{PL}\left(\mathrm{Si}{O}_2\right)}\mathrm{dT}}^{T_{\mathrm{ad}}}}^{T_{m\left(\mathrm{Si}{O}_2\right)}}$ in the formula, the phase transition is not expressed, but has been taken into account in the calculation. From this equation, T is calculated_0C417K. In the calculation, the error range of the liquid phase amount is +/-1.0%, the error range of the temperature is +/-5 ℃, and the amount of 2-5% of water glass and 0.2-3% of carboxymethyl cellulose are not considered in the calculation.

As will be further apparent from the above description and calculations, θ is determined according to the present invention₁Or theta_1CProvided by experiments. To ensure that theta is reached during the SHS reaction₁Or theta_1CBy adding defined amounts of additives to the reaction system and designing the preheating temperature T₀Or T_0CTo achieve the final product of the invention, the ignition temperature T is the actual self-propagating reaction_KTo complete.

T_KThe determination principle is to take the value theta₁Within a prescribed range of T₀Or has a stable fixed value theta_1CMinimum preheating temperature ofT_0CAdding 300-400 ℃ again; the additive is determined by adding 1-40% of the total amount of the reactants₀In many cases, the amount added may take an upper limit, θ₀When the amount is smaller, the amount to be added may take a lower limit; theta₁Or theta_1CAnd T₀Or T_0CThe determination is generally based on the principle that when different additives and different amounts of additives are added, if theta₀If<40%, theta should be controlled₁(or theta)_1C) In the range of 40-60% to calculate T₀(or T)_0C) If theta is greater than theta₀In the range of 40-60%, theta should be controlled₁(or theta)_1C) In the range of 50-70% to calculate T₀(or T)_0C) If theta is greater than theta₀If>60%, theta should be controlled₁(or theta)_1C) 60 ^ e80% range to calculate T₀(or T)_0C)。

The method for preparing the foamed ceramic material by utilizing self-propagating high-temperature synthesis provided by the invention has different specific control parameter quantities for different SHS reaction systems, such as for The controlled additive can be metal Ti, Cr, Zr, W, Mo, whose content is controlled in the range of 1-10%, or ceramic material Al₂O₃、SiO₂、ZrO₂The amount of SiC is controlled within 1-15%, and metal and ceramic materials can be added simultaneously, but the total addition amount of the SiC and the ceramic materials is 1-15% of the reactant amount. Designed liquid phase amount theta in SHS reaction process₁Controlling the concentration to be within the range of 40-60%; designed preheating temperature T of blank₀Should be controlled within the range of 410-1380K, and the actual ignition temperature T is controlled during the sintering process by using the SHS reaction_KShould get T₀Average of the upper and lower limits of (1), T_KThe range of (1) is 560 to 1265K.

For the To a To a To a Preparation of foamed ceramic material by SHS reaction, designed system liquid phase quantity theta₁(or theta)_1C) The kind and amount of the additive, and the designed preheating temperature T of the green body₀(or T)_0C) And the ignition temperature T at which the SHS reaction actually proceeds_KThe ranges are listed in the attached table and are not listed here.

Table 1 shows the SHS reaction process parameters for preparing the foamed ceramic material. The table details 5 equations for performing the SHS reaction, theoretical parameters, process control parameters and control quantities.

TABLE 2 is And (3) a process parameter control calculation example for preparing the foamed ceramic material by the system.

Detailed in the table The system utilizes SHS reaction to prepare the foamed ceramic material, and different liquid phase quantities theta in the designed system₁And to ensure theta₁The amount of the additive, the type and amount of the additive, and the designed preheating temperature T of the blank₀And the actual ignition temperature T for the SHS reaction_KThe relationship between them.

TABLE 3 is And (3) a process parameter control calculation example for preparing the foamed ceramic material by the system.

The amount of the liquid phase designed is calculated in detail in the table, and the fixed value theta is stable according to the variation of the type and amount of the additive_1CAnd to ensure theta_1CThe amount of the additive, the controlled different amounts of the additive, the minimum design preheating temperature T of the blank_0CAnd the actual ignition temperature T for the SHS reaction_KThe relationship between them.

TABLE 4 is And (3) a process parameter control calculation example for preparing the foamed ceramic material by the system.

The table shows that the fixed value theta of the system, which is stable with the change of the additive and the amount thereof and the change of the liquid phase amount, is calculated in detail_1CAnd to ensure theta_1COf valueThe amount, the different additives added and the amount thereof are equal to the minimum designed preheating temperature T of the blank_0CAnd the actual ignition temperature T at which the reaction of SHS proceeds_KThe relationship between them.

TABLE 5 is And (3) a process parameter control calculation example for preparing the foamed ceramic material by the system.

The table calculates the fixed value theta of the system liquid phase quantity which is still stable along with the changes ofdifferent additives and the quantities thereof in detail_1CAnd theta controlled for assurance_1CValue, and the minimum design preheating temperature T of the additive added in different amounts and compositions_0CActual ignition temperature T for carrying out the SHS reaction_KThe relationship between them.

TABLE 6 is And (3) a process parameter control calculation example for preparing the foamed ceramic material by the system.

The liquid phasor theta of the system is calculated in detail in the table₁The amount of liquid phase theta is designed to be greatly changed along with the change of the amount and the type of the additive₁And to ensure theta₁The values of (A) and (B), the amounts and types of additives added, the designed preheating temperature T of the green body₀And the actual ignition temperature T for the SHS reaction_KThe relationship between them.

Table 7 is a table comparing the performance effects of the present invention with the prior art.

The invention provides a method for preparing a foamed ceramic material by utilizing self-propagating high-temperature synthesis (SHS), which mainly comprises four steps of preparation of slurry [1], impregnation of a foam carrier [2], drying of a green body [3]and sintering of the green body [4].

Firstly, according to the proportioning components of the slurry, adding water accounting for 50-100% of the total weight of the formula materials, uniformly stirring to obtain slurry [1],

secondly, the polyurethane foam plastic which is used as a slurry carrier and has the aperture of phi 0.3-3.0 (mm, the same below) is made into a required large-small shape, the polyurethane foam plastic is soaked in the slurry (2)for about 10-15 minutes, the excess slurry is taken out and extruded (40-60% of the slurry is generally extruded),

thirdly, heating the polyurethane foam plastic (called blank or blank) adhered with the mixture slurry to 200-300 ℃, drying [3]to volatilize the foam plastic, shaping the blank,

the fourth step, drying [3]]Heating the blank directly to T_KTemperature (error + -5 deg.C), then, ignition operation is carried out by oxygen-B fast flame or electrical heating with metal W, Mo wire at one end, the green body is sintered during completion of SHS reaction [4]](or preparing) the composite foam ceramic material.

Finally, after being refitted and detected to be qualified, the material is ready for use.

The method has the main advantages that ① process is simple, high-temperature sintering equipment is omitted, energy and investment are saved, ② production period can be greatly shortened, general sintering time is only 10-40 seconds, a product prepared from ③ has good high-temperature resistance angry, refractoriness is larger than 1800 ℃, thermal shock resistance of ④ is larger than 40 times at 20-1000 ℃, l000C compressive strength is 2-5 MPa, and the cost of&gtttransformation = fifth "&gtt/t&gttis low.

The technical properties of the present invention are compared with those of the prior art and are shown in Table 7.

The following is a description of the drawings.

FIG. 1 is a block diagram of the process flow for preparing foamed ceramic material by using self-propagating high-temperature synthesis (SHS reaction) method according to the present invention.

It is completed by the procedures of slurry preparation [1], foam carrier impregnation [2], green body drying [3]and SHS reaction sintering [4]. The arrow directionindicates the process progress direction.

FIG. 2 shows the high temperature synthesis of TiB by SHS reaction using Ti +2B system₂Preparation of a foamThe sintering process of the ceramic material is shown schematically.

In the blank body [5]]One end head (6)]Ignition is carried out at TK temperature, and the blank [5]]From the reaction (Ti +2B) end of (C) immediately [6]]The synthesis of TiB begins₂Ceramic material [7]]The combustion wave is directed rapidly towards the unreacted body [5]]Directional expansion, in which the arrows point to unexpanded regions, in the formed ceramic material [7]]And a blank body [5]]With a heat affected zone [8]in between](shaded) and finally, the entire synthetic ceramic foam material TiB₂[7]And is terminated.

The details of the invention are further illustrated below with reference to specific examples of the invention:

example 1:

the performance requirements of the foamed ceramic filter for filtering molten steel are as follows: the refractoriness is more than 1600 ℃, the compression strength at normal temperature is 2.0MPa, the compression strength at high temperature is 1.0MP, the size (mm, the same below) is required to be 100 multiplied by 22, the invention is prepared by adopting the method, and the steps are as follows:

first, preparing a slurry

The filter material is made of Al due to the required high refractoriness₂O₃And TiB₂And (4) forming. According to the reaction equation Respectively taking 90g of 200-270 mesh Al powder and TiO₂80g of powder, B₂O₃70g of powder, additive Al₂O₃Taking 24g of the mixture, adding 12g of waterglass, 4g of carboxymethyl cellulose and 200ml of water into the mixture, and mixing the mixture in a ball mill for 20 minutes to prepare the required slurry, wherein the weight percentage of the required slurry is 10 percent of the total weight of the reactants (the same applies below).

Second, control parameters are calculated according to thermodynamics

The adiabatic temperature of the system is taken as T_ad2303K and adding Al₂O₃And Al produced₂O₃All melt, at the time, the controlled liquid phase quantity theta of the system_1C73.5%, the minimum design preheat temperature was calculated as T_0C444K, take T_0C+350 ℃ as the actual ignition temperature of the body, i.e. T_K＝794K＝521℃。

Thirdly, preparing a blank

Considering that there is partial shrinkage after sintering, polyurethane foam with average pore diameter of 3.0mm and enlarged size of 110X 25 is taken out and dipped in the prepared slurry for 15 minutes, after uniform dipping, the polyurethane foam is taken out and extruded to form slurry with volume of about 50 percent, and then the slurry is put into an electric heating oven to be heated to 300 ℃ at the heating rate of 4 ℃/minute and is kept for 1 hour, at this time, the polyurethane foam is volatilized, and a blank is dried and shaped.

The fourth step, sintering operation

And putting the dried and shaped blank into a box-type resistance furnace, heating to 521 +/-5 ℃, electrically heating by using a W wire with the diameter of 0.5mm at the temperature, and igniting one end of the blank, wherein the voltage of the W wire is 30V and the current is 60A. After one end is ignited, the combustion wave rapidly expands to the unreacted area for about 40 seconds, and the SHS reaction is completed.

Fifth step, dressing inspection

The filter is made in a size slightly larger than the specified size, and needs to be slightly refitted after sintering to reach the sizeThe specified 100X 22, the filter prepared by detection has the following effective components: al (Al)₂O₃73.5％，TiB₂26.5 percent, the normal temperature compressive strength of the filter is 3.0MPa, the high temperature compressive strength at 1000 ℃ is 2.7MPa, the heat shock resistance at 1000 ℃ is more than 40 times, and the refractoriness is more than 1800 ℃. Practical application to filtration 45^#Molten steel has good effect.

Example 2:

the performance requirements of the foamed ceramic filter for the internal combustion engine tail gas purification test are that the refractoriness is more than 1500 ℃, the normal-temperature compressive strength is 4.0MPa, and the high-temperature thermal shock resistance is more than 40 times at 1000 ℃. The dimension of the product prepared by the technology is phi 150 multiplied by 40(mm, the same below), and the preparation process is as follows:

first, slurry preparation

The filter is made of TiB2 ceramic material according to the performance requirement of the filter, and therefore, the filter is made according to the reaction formula Respectively taking 240g and 110g of Ti powder and B powder with the granularity of 250-320 meshes, respectively, adding Cr powder and SiO₂The amount of the powder was 5% and 10% of the total weight of the above reactants, i.e., 17.5g and 35g, respectively. Then 15g of water glass and 5g of carboxymethyl cellulose are added, and then 300ml of water is added and mixed in a ball mill for 15 minutes, thus preparing uniform slurry.

And secondly, calculating control parameters according to thermodynamics.

The system T_ad3193K, and controlling the liquid phase amount theta₁When the preheating temperature is 40%, the lower limit value of the designed preheating temperature is 760K and theta₁=60% designing the upper limit value of the preheating temperature to be 1020K, and taking the actual ignition temperature T of the blank_K890K, i.e. 617 ℃.

Thirdly, preparing a blank

The polyurethane foam plastic with the average pore diameter of 0.3 and the size of phi 165 x 45 (the size is slightly larger than the actual size in consideration of the shrinkage allowance after processing) is soaked in the slurry for about 10 minutes, the slurry with the volume of about 60 percent is extruded after the uniform soaking, then the polyurethane foam plastic is put into an electric heating oven to be heated to 300 ℃ at the speed of 3 ℃/minute, the temperature is kept for 1 hour, the foam plastic is volatilized, and a blank body is formed.

The fourth step, sintering operation

Putting the dried and molded blank into a box-type resistance furnace, heating to 617 +/-5 ℃, and at the temperature, electrically heating and igniting one end of the blank by using a W wire with the diameter of 0.5 phi, wherein the voltage of the W wire is 25V, the current is 50A, and the sintering process of the SHS reaction is completed in about 10 seconds to prepare the required TiB₂A foam ceramic filter.

Fifth step, dressing inspection

Slightly trimming the sintered filter to reach the filter size of phi 150X 40 and TiB as the effective component₂87.1% of SiO₂8.6 percent of Cr, 4.3 percent of Cr, and mechanical properties: the compression strength at normal temperature is 5.3MPa, the compression strength at high temperature of 1000 ℃ is 4.8MPa, the thermal shock resistance at 1200 ℃ is more than 40 times, the refractoriness is more than 1800 ℃, and the carbon soot trapping effect is good when the carbon soot trapping agent is actually applied to a tail gas purification test.

The following examples 3, 4, 5 and 6 have the same preparation steps as those of examples 1 and 2, so that the three steps of preparation of a green body, sintering operation and dressing test in the implementation steps are omitted, and the examples 1 and 2 can be referred to. Examples 3, 4, 5, 6 below only show the preparation of slurries, the use of thermodynamically calculated control parameters and the analysis of the final product composition.

Example 3:

preparation of a ceramic foam filter for copper water filtration having a size of 85X 15.

Degree of refractoriness according to its performance requirementsMore than 1300 ℃, the high-temperature compressive strength is 1.8MPa, the normal-temperature compressive strength is 2.8MPa, and Al is selected₂O₃Cr and SiO₂The material is used for manufacturing a filter. According to the reaction equation Respectively taking 200-270 mesh Al powder and Cr₂O₃54g and 152g of powder and SiO as additive₂Taking 82.4g of water glass, adding 11g of water glass, 6g of carboxymethyl cellulose and adding 250ml of water into 40 percent (wt percent, the same below) of the total weight of the reaction materials, mixing the mixture in a ball mill for 15 minutes to prepare slurry, and taking T in the system according to thermodynamic calculation_adWhen the liquid phase amounts are controlled to 60% and 80%, respectively, the design preheating temperature T is calculated₀Has an upper limit of 775K and a lower limit of 990K, taking the actual ignition operating temperature T_K883K (610 + -5 deg.C), and then by 3, 4, and 5 steps of example 1 or 2, a ceramic foam filter with Al as the final component is prepared₂O₃35.4% of Cr, 36.0% of Cr and SiO₂Accounting for 28.6 percent. Example 4:

a ceramic foam filter for aluminum liquid purification having a size of 90X 20(mm, the same applies hereinafter) was prepared.

According to the performance requirements, the (ZrO) has the refractoriness of more than 1000 ℃, the normal temperature compressive strength of 2.0MPa and the high temperature compressive strength of 1.4MPa₂+ Cr) ceramic material with Al₂O₃The additive is used for preparing the filter.

According to the reaction equation Respectively taking 200-300 meshes of Zr powder and Cr₂O₃The powder is 136.5 g and 152g, respectively, and the additive is Al₂O₃Taking 28.9g of 28.9 percent (wt percent) of the total weight of reactants, adding 20g of water glass, 10g of carboxymethyl cellulose and 350ml of water, mixing in a ball mill for 15 minutes to prepare slurry, and taking the volume of T according to thermodynamic calculation_adControl the liquid phase amount theta as 2303K_1C41.8%, the minimum design preheating temperature T is calculated_0C350K, and taking the actual blank ignition temperature T_K650K, i.e. 377 ℃ ± 5 ℃.

Then, the procedure of example 1 or 2 was followedThe operation of 3, 4 and 5 steps in the step can prepare the foam ceramic filter, and the final components are as follows: ZrO (ZrO)₂58.1 percent of Cr, 32.8 percent of Cr and Al₂O₃Accounting for9.1 percent.

Example 5:

a ceramic foam filter for cast iron filtration having dimensions of 120X 30(mm, the same applies hereinafter) was prepared using the technique of the present invention.

According to the performance requirements, the refractoriness is more than 1600 ℃, the normal temperature compressive strength is 2.2MPa, and the high temperature compressive strength is 1.3MPa (Al)₂O₃+ TiC) ceramic material made of Ti and SiO₂The additive is used for preparing the filter.

According to the reaction equation Respectively taking 90g, 200g and 30g of Al powder, Ti powder and C powder of 200-270 meshes, and adding Ti powder and SiO powder₂Powder, accounting for 5 wt% of the additive (the same applies below), each 16g, water glass 8g, carboxymethyl cellulose 10g, and water 260ml are added, mixed in a ball mill for 15 minutes, and made into slurry. According to thermodynamic calculation, the system takes T_adControl the liquid phase amount theta as 2303K_1CIs 57.4%, the minimum design preheating temperature T is calculated_0C535K, and the actual blank ignition temperature is T_K935K, i.e. T_K＝662±5℃。

Then, the operation is carried out according to the steps 3, 4 and 5 of the embodiment 1 or 2, so as to prepare the foamed ceramic filter, wherein the final components are as follows: al (Al)₂O₃48.3 percent of TiC, 42.6 percent of SiO₂4.55 percent of Ti and 4.55 percent of Ti.

Example 6:

the technique of the invention is adopted to prepare the foam ceramic filter with the size of phi 150 multiplied by 50(mm, the same below) for the tail gas of the internal combustion engine.

According to the performance requirements: the refractoriness is more than 1600 ℃, the normal temperature compressive strength is 3.5MPa, the thermal shock resistance at the high temperature of 1000 ℃ is more than 50 times, and the adopted foam ceramic material is TiB₂The difference from example 2 is mainly the additives and their amounts.

According to the reaction equation Respectively taking 240g and 110g of Ti powder and B powder of 270-320 meshes, taking 3.5g of Cr powder as an additive accounting for 1 percent of a reactant, adding 15g of water glass, 7g of carboxymethyl cellulose and 270ml of water, mixing for 15 minutes in a ball mill, and preparing into slurry. Taking T according to thermodynamic calculation_ad3193K, when the liquid phase amount is controlled to be 40% and 60%, the upper limit and the lower limit of the designed preheating temperature are 410K and 710K respectively. Taking the actual blank ignition temperature T_KIs 560K, i.e. T_K＝287℃±5℃。

Then, the steps 3, 4 and 5 of the step 1 or 2 are carried out to manufacture the ceramic foam filter. The final composition is TiB₂99.0 percent of Cr and 1 percent of Cr.

It should be noted that, in the calculation of the ingredients of the examples, about 1% of impurities in the water glass, carboxymethyl cellulose and reactants were not included, and this effect was not considered in the thermodynamic calculation.

TABLE 1 SHS reaction Process parameters for the preparation of foamed ceramic materials

TABLE 2 Example forcontrolling and calculating technological parameters of preparing foamed ceramic material

TABLE 3 Example for controlling and calculating technological parameters of preparing foamed ceramic material

TABLE 4 Example for controlling and calculating technological parameters of preparing foamed ceramic material

TABLE 5 Process parameter control meter for preparing foamed ceramic material by systemExamples of the design

TABLE 6 Example for controlling and calculating technological parameters of preparing foamed ceramic material

Table 7 comparison of the performance and effects of the present invention and the prior art

	The invention	Comparison technique	Technical effects of the invention
				Additive material	Metal powder: cr, Ti, Zr, W、Mo Ceramic powder: al (Al)2O3、SiO2、 SiC、ZrO2	Y2O3(1～5％)	Small amount of metal powder to raise mechanical strength The ceramic powder can improve the high temperature resistance Adding higher cost Y2O3
Adhesive agent	2 to 5 percent of water glass Carboxymethyl cellulose O.2～3％	Swelling plus or minus 2 to 5 percent Carboxymethyl cellulose 1 ℃ 3％ 3-6% (or α - 1-2% of starch	Phosphoric acid without addition of harmful substances
				Sintering time Sintering temperature	At TKTemperature reaction sintering " Finish in 10-40 seconds TKThe range of 366 to 1457K (93～1184℃)	At a high temperature of 1500 ℃ 1650℃ Sintering for 1-6 h	Reduce the cost Shorten production cycle
High temperature apparatus	1200 ℃ medium temperature furnace	1650 ℃ high-temperature furnace	Omitting high-temperature sintering equipment
				Main body material Material composition	TiB2，Al3O3+ TiB2Al2O3+TiC， Al2O3+Cr ZrO2+Cr	Al2O3+SiO2 Al2O3+SiO2+ZrO2	High strength Good high temperature resistance
Performance of	The resistance to rapid cooling and rapid heating is more than 40 times (20～1000℃) Refractoriness of more than 1800 DEG C Strength at room temperature 3～6MPa High temperature (1000 ℃ C.) strength 2～5MPa	The resistance to rapid cooling and rapid heating is more than 30 times (20～1000℃) Refractoriness 1650E 1800℃ Strength at normal temperature of 2-5 MPa High temperature (1000 ℃ C.) strength 1～3MPa	Superior to the comparative technique

Claims (7)

1. A method for preparing foamed ceramic material by Self-propagating High-temperature synthesis (SHS for short) comprises the technical processes of preparing slurry [1], dipping [2], drying [3]and sintering [4], and is characterized in that:

a) the prepared slurry comprises two or more than two stoichiometric samples with particle size of more than 200 meshes, can perform SHS reaction and generate partial liquid phase (theoretical calculated value theta)₀) The reactant powder of (3); 1-40% (wt% of the total weight of the reactants, the same applies below); water glass accounting for 2-5% of the total weight of the reactants; carboxymethyl cellulose accounting for 0.2-3.0% of the total weight of the reactants; uniformly stirring the materials into slurry by using water accounting for 50-100% of the total weight of the added materials,

b) the sintering of the green body is finished by utilizing a self-propagating high-temperature synthesis (SHS) method,

c) the amount of liquid phase (theta) controlled in the system during the completion of the SHS reaction₁Or theta_1C) 40 to 80 percent of the total amount of the organic silicon,

d) actual ignition temperature T of green body sintering_K。

2. The method for preparing ceramic foam material using self-propagating high-temperature synthesis (SHS) as claimed in claim 1, wherein the additives are high-melting metal powder and ceramic powder, the commonly used high-melting metal powder includes Ti, Cr, Zr, Mo and W, and the ceramic powder includes Al₂O₃、SiO₂、ZrO₂And SiC.

3. A method of using self-propagating plant as claimed in claim 1A method for preparing foamed ceramic material by high temperature synthesis (SHS) is characterized in that the designed preheating temperature T of a blank body₀Upper and lower limits or minimum design preheating temperature T_0CAll the above steps are carried out in a way that 40-80% of liquid phase amount theta exists when the SHS reaction is carried out in a guaranteed system₁Or theta_1COn the premise of (1), the method is obtained through thermodynamic calculation.

4. The method for preparing foamed ceramic material by self-propagating high-temperature synthesis (SHS) as claimed in claim 1, wherein the controlled liquid phase amount θ of the green body in the SHS reaction is 40-80%₁Or theta_1CIs a theoretical calculation of theta based on the liquid phase quantity₀And determined by thermodynamic calculation and experiments by controlling the types and the amounts of the additives added.

5. A method for preparing a foamed ceramic material by self propagating high temperature synthesis (SHS) according to claim 1 or 3 or 4, wherein if θ is selected for different additives and different addition amounts₀If<40%, theta should be controlled₁In the range of 40-60% to calculate T₀Or T_0C(ii) a If theta is greater than theta₀In the range of 40-60%, theta should be controlled₁In the range of 50-70% to calculate T₀Or T_0C(ii) a If theta is greater than theta₀If>60%, theta should be controlled₁In the range of 60-80% to calculate T₀Or T_0C。

6. The method for preparing foamed ceramic material by self-propagating high-temperature synthesis (SHS) as claimed in claim 1, wherein the SHS reaction is used to obtain the actual ignition temperature T of the body_KThe value taking method comprises the following steps: when the preheating temperature T is designed₀Continuously varies, and theta₁T is continuously changed within a range of 40-80%_KGet T₀The average of the upper and lower limits of (a); when the preheating temperature T is designed₀Is continuous within a certain rangeChange, and theta₁Is a stable fixed value (called theta)_1C) When, T_KShould takeTo this fixed value (theta)_1C) Minimum design preheat temperature (called T)_0C) Then adding 300-400 ℃.

7. The method for preparing foamed ceramic material by self-propagating high-temperature synthesis (SHS) according to claim 1, wherein the manufacturing process comprises: the formula of the prepared slurry is added with water and then uniformly mixed in a ball mill for 15-20 minutes to prepare the slurry [1]]Then processing the polyurethane foam plastic with the aperture of phi 0.3-3.0 mm into the required shape, and then dipping the shape in [2]]In the slurry [1]Taking out and extruding 40-60% slurry after 10-20 min, maintaining at 200-300 deg.c for about 1 hr, and stoving [3]]Into a green body [5]Then, the mixture is put into a furnace and heated to the actual ignition reaction temperature T_KAnd at that temperature, with oxygen-acetylene flame or metal W, M₀And (3) electrically heating the wires to perform sintering ignition, completing the SHS reaction process, manufacturing the SHS into a product, and finally, finishing and detecting the product to be qualified for later use.