Coefficient Of Thermal Expansion Values Research Articles

High temperature thermomechanical properties of a microcracked model refractory material: A silica-doped aluminium titanate

An aluminium titanate based (AT) material doped with silica was investigated as refractory model material in order to highlight its thermomechanical properties through various techniques of characterization operating at high temperature such as ultrasonic pulse echography technique operating in long bar mode, acoustic emission, dilatometry and tensile test measurements up to 1400 °C. Young's modulus (MoE) as a function of temperature evolves in the form of a large hysteresis loop with a maximum value of about 170 GPa due to the healing of diffuse microcracks during heating. A sharp decrease in MoE occurs on cooling at about 780 °C, corresponding to the re-opening of the microcracked network due to a high level of stress around AT grains. In addition, during cooling, the dilatometric analysis shows a quasi-linear shrinkage followed by a sudden non-linear expansion from 750 °C. The thermal expansion coefficient value determined between 1100 °C and 750 °C is about 8.8 10−6 °C−1. By recording the evolution of the cumulative number of hits as a function of temperature, the results of the acoustic emission clearly confirm the resurgence of microstructural defects at 780 °C. The incremental tensile loading test performed at 1400 °C shows a greater degree of nonlinearity suggesting a higher flexibility of the studied AT due to both the microcracks network and the low viscosity of intergranular glassy phase. Symmetric alternating loading tests have highlighted that the viscous contribution in the viscoelastic behaviour of such materials is increasing from 850 H °C to 1400 H °C as the viscosity of the silica-riched amorphous phase is decreasing. These results are very useful to understand the more sensitive parameters involved in the high thermal shock resistance of aluminium titanate.

Growth of crack free Nd2Ti2O7 thin films using La0.7Sr0.3MnO3±δ as a template layer for high temperature pyroelectric applications

Neodymium titanate () is a ferroelectric as well as a pyroelectric material with a transition temperature of 1480 °C. Hence, offers potential to be utilized as high temperature pyroelectric sensor in both bulk and thin film form. In this work, bulk powders were synthesized using solid state reaction method, which were later pressed into the pellets. Later, thin films of were deposited on commercially available platinized(111) silicon and Si(100) substrates via pulsed laser deposition technique. The huge c/a ratio (∼1.695) and the thermal expansion mismatch with most of the commonly used substrates like silicon and platinized silicon, results into crack formation in thin films. Crack formation on thin film, which deteriorates pyroelectric property of film, was suppressed by the introduction of buffer layer between the film and substrate. The calculated value of thermal expansion coefficient of is 2.86 × 10−5 °C−1. Moreover, thermally generated strain between film and platinum substrate was found to be around 2%. The piezoresponse force microscopy experiment confirms the existence of ferroelectric domains in the film. Pyroelectric coefficient (p) calculated from the pyrocurrent studies was estimated around 3.52 and 13.6 μC/m2K in the bulk and thin film, respectively.

Low Expansion Glass-Ceramics Using Industrial Waste and Low-cost Aluminosilicate Minerals: Fabrication and Characterizations

The recycling of the wastes towards value added product development has become a prime challenge. In this work, a low thermal expansion glass-ceramic material based on ternary LAS (Li2O-Al2O3-SiO2) system has been prepared by adopting meltquenching route using industrial waste (blast furnace slag) and low-cost aluminosilicate minerals (China clay and pyrophyllite) at relatively low melting temperature (∼1450°C). A part of the precursor powder for pristine glass has also been prepared by sol-gel processing utilizing Li2CO3 and Al(NO3)3.9H2O to obtain better homogeneity in the glass composition vis-à-vis glass-ceramics at lower melting temperature. Thermal properties of the material have been characterized to optimize the nucleation and crystallization temperatures for converting glass to glass-ceramics. Phase structure and surface morphology of the glass-ceramics have been analyzed by X-ray diffraction (XRD) and field emission scanning electron microscopy. XRD study reveals the presence of lithium aluminosilicate as a major phase at the crystallization temperature of 730°C. The developed glass-ceramics show a low thermal expansion coefficient (CTE) value of (19±0.5)×10–7/°C in the temperature range of 30°-500°C. The present work can unfold an avenue towards conversion of waste into wealth in the form of low CTE glass-ceramics for possible application as cook-top plate of LPG gas oven.

Crystal Structure and Properties of Complex Oxides (Nd,Ba)(Co,Fe)O3–δ

The homogeneity ranges and crystal structure of solid solutions of Nd1−x1BaxCo1−y1FeyO3−δ3 composition were detected. Depending on introduced barium concentration Nd1−x1BaxCo1−y1FeyO3−δ3 oxides have been crystallized in the orthorhombically distorted (x = 0.05, sp. gr. Pbnm), cubic (0.6 ≤ x ≤ 0.9, sp. gr. Pm-3m) perovskite structure or double perovskite structure NdBaCo2−x2FexO5+δ5 (0.0 ≤ x ≤ 1.4, sp. gr. P4/mmm). The dependencies of unit cell parameters versus composition of the Nd1−x1BaxCo1−y1FeyO3−δ3 solid solutions were obtained. It is shown that the values of oxygen nonstoichiometry in Nd1−x1BaxCo1−y1FeyO3−δ3, determined by a thermogravimetric method within the temperature range 298–1373 K in air, increased with the raise of barium and cobalt content. Average values of thermal expansion coefficients for the Nd1−x1BaxCo1−y1FeyO3−δ3 oxides (0.8 ≤ x ≤ 0.9 and 0.7 ≤ y ≤ 0.9) visibly increased with temperature from (13.5–14.5) × 10–6 K–1 at 300–700 K up to (23.2–26.2) × 10–6 K–1 at 700–1373 K.

Ultralight Functionally Graded Hybrid Nanocomposites Based on Yttrium and Silica-Reinforced Mg10Li5Al Alloy: Thermal and Tribomechanical Properties.

Despite the amazing properties of lightweight Mg10Li5Al alloy, its use in industrial applications is highly limited due to its low mechanical properties, wear resistance, and coefficient of thermal expansion (CTE). In this context, this work aimed to improve the above properties without sacrificing the important benefit of this alloy being lightweight. Therefore, function grade composites (FGCs) were prepared based on the Mg10Li5Al alloy reinforced by yttrium (Y) and silica fume using the powder metallurgy technique. Then, the nanocomposite's microstructure, mechanical properties, artificial aging, wear resistance, and thermal expansion were examined. The results indicated that the precipitation (MgAlLi2), softening (AlLi2), and Mg24Y5 phases were formed in high-reinforced samples during high-energy milling. Furthermore, the addition of reinforcements accelerated the decomposition from the MgAlLi2 phase to the Al-Li phase (softening point). For the layer containing the highest reinforcement content, microhardness, strength, and Young's modulus improved up to 40, 22.8, and 41%, respectively, due to the combined effect of the high strength of silica fume and the dispersion strengthening Mg24Y5 phase. Meanwhile, the same sample exhibited a remarkable improvement in wear rate and the CTE value to about 43 and 16.5%, respectively, compared to the non-reinforced alloy.

The relationship of hot and cold rolling processes with the structure and properties of invar 36

Invar 36 with both high hardness and low coefficient of thermal expansion (CTE) is desired in aerospace, defense, aviation and electronics industries. In this study, 20% cold rolling and 50% hot rolling processes were applied to the commercial invar 36 without adding any other alloying elements. In the cold rolling process, martensitic transformation was not observed due to the high stacking fault energy of invar 36. The (220) intensity decreases with hot rolling under the recrystallization effect, while it increases with cold rolling. While the average grain size was 300 μm as-casting, it was reduced to about 50 μm by hot rolling. The lowest CTE value was obtained in the cold rolled sample as 0.331 × 10−6/°C. The Curie temperature was found to be approximately 185 °C by differential scanning calorimetry (DSC) analysis. There was no significant change in microhardness of as-cast and hot rolled samples. The maximum microhardness is 220.1 HV5 in the cold rolled sample.

Near-Zero Thermal Expansion and High Heat-Resistance Polyimide Films Based on a Symmetric and Rigid Pyrazine Structure

Regarding the applications of polyimide (PI) films in emerging flexible devices and precision apparatus, their low coefficient of thermal expansion (CTE), especially near-zero expansion, is an urgent requirement for weakening the internal stress between the organic/inorganic layers. Other properties of PI films including the high heat-resistance and superior toughness are also demanded in actual scenarios. Herein, a set of PI films was developed by copolymerization of 2,5-bis(4-aminophenyl)pyrazine (PRZ) into a pyromellitic dianhydride (PMDA)/4,4′-oxydianiline (ODA) system. The monocrystal analysis of the PRZ monomer reveals its rigid, symmetric, and nearly coplanar steric structure. Thanks to the synergy and balance of flexible ODA and rigid PRZ units in PI chains, the near-zero expansion, high heat-resistance, and optimal mechanical properties of the PI films are simultaneously achieved. Particularly, the PI film with ODA/PRZ = 4.5/5.5 presents a near-zero CTE of −0.41 ppm/K, high glass transition temperature (Tg) of around 417 °C, superior fracture strength of 191 MPa, and initial modulus of 3.83 GPa. Interestingly, via adjusting the ODA/PRZ ratios, the precise control of CTE values can be realized, enabling the thermal expansion matching of PI films on broad types of device substrates, e.g., Cu (15–17 ppm/K) and Si (3–5 ppm/K).

Transport properties of LaYbO3-based electrolytes doped with alkaline earth elements

The rapid development of efficient high-temperature electrochemical devices stimulates the search for new electrolytic materials with high conductivity and excellent chemical stability. From this point of view, lanthanum-containing perovskites can be considered as suitable materials for solid oxide fuel cell applications. In this work, the successfully synthesis and comprehensive study of acceptor-doped lanthanum ytterbates, La1–xMxYbO3–δ (M = Ca, Sr, Ba; x = 0, 0.05, 0.1) is described. X-ray diffraction analysis showed all samples to possess an orthorhombic structure with the space group Pna21, whose stability was confirmed at temperatures up to 1000 °C. The high chemical stability of the materials with respect to carbon dioxide and water vapor was confirmed by SEM and XRD methods. The dilatometry data allowed the determination of thermal expansion coefficient values of ceramic samples, which are close to those for conventionally used YSZ electrolytes. The transport properties of the ceramic were studied in a wide range of temperatures (300–900°C) and oxygen partial pressures. It was found that ytterbates doped with 5 and 10 wt.% of strontium and 5 wt.% of barium exhibited the high electrical conductivity among other considered materials. Thus, these materials can be considered as promising proton-conducting electrolytes for various electrochemical devices.

Tuning Cu-Content La1-xSrxNi1-yCuyO3-δ with Strontium Doping as Cobalt-Free Cathode Materials for High-Performance Anode-Supported IT-SOFCs.

Cu-content La1-xSrxNi1-yCuyO3-δ perovskites with A-site strontium doping have been tuned as cobalt-free cathode materials for high-performance anode-supported SOFCs, working at an intermediate-temperature range. All obtained oxides belong to the R-3c trigonal system, and phase transitions from the R-3c space group to a Pm-3m simple perovskite have been observed by HT-XRD studies. The substitution of lanthanum with strontium lowers the phase transition temperature, while increasing the thermal expansion coefficient (TEC) and oxygen non-stoichiometry δ of the studied materials. The thermal expansion is anisotropic, and TEC values are similar to commonly used solid electrolytes (e.g., 14.1 × 10-6 K-1 for La0.95Sr0.05Ni0.5Cu0.5O3-δ). The oxygen content of investigated compounds has been determined as a function of temperature. All studied materials are chemically compatible with GDC-10 but react with LSGM and 8YSZ electrolytes. The anode-supported SOFC with a La0.95Sr0.05Ni0.5Cu0.5O3-δ cathode presents an excellent power density of 445 mW·cm-2 at 650 °C in humidified H2. The results indicate that La1-xSrxNi1-yCuyO3-δ perovskites with strontium doping at the A-site can be qualified as promising cathode candidates for anode-supported SOFCs, yielding promising electrochemical performance in the intermediate-temperature range.

Tuning high and low thermal expansion coefficients of Li2O–BaO–Al2O3–B2O3–SiO2/quartz LTCC composites by replacing quartz partly with α-Al2O3 or ZrO2

Low-temperature co-fired ceramics (LTCC) with adjustable coefficients of thermal expansion (CTE) based on Li 2 O–BaO–Al 2 O 3 –B 2 O 3 –SiO 2 /quartz LTCC composites (glass/ceramics) have been employed in electronic packaging to address the interface thermal mismatch problem caused by different thermal expansion coefficients. In the present study, sintering behavior, phase structure, and CTE of LTCC composites is controlled by replacing quartz partly with α-Al 2 O 3 or ZrO 2 . Accordingly, LTCC composites with the highest and lowest CTE values are achieved. The results show that the major phases of α-Al 2 O 3 substituted LTCC composites are hexacelsian, β-spodumene, and virgilite. Correspondingly, CTE values are in the range of 5.67–8.62 × 10 −6 /°C. Whereas, ZrO 2 substituted LTCC composites have exhibited increased CTE values to 12.27 to 13.2 × 10 −6 /°C with major phases of cristobalite, hexacelsian, and bazirite. Moreover, the negative effects of phase transformation of hexacelsian can be inhibited to a certain extent upon substitution of α-Al 2 O 3 up to 15 wt%. This work provides suitable methods for preparing LTCC composites with gradient CTE and resolving the thermal mismatch effects at different interfaces (e.g., chip/LTCC, metal electrode/LTCC) in electronic packaging structures.

Towards new zero-thermal-expansion materials: Li-free quartz solid solutions stuffed with transition metal cations

Stuffed aluminosilicate quartz solid solutions (Qss) represent the main functional component of state-of-the-art zero-thermal-expansion glass-ceramics. For the first time, we present the synthesis of Li-, Mg- and Zn-free Qss solely stuffed with transition metal cations (Fe2+, Ni2+, Co2+); partial Li+ co-doping enables also significant Mn2+ incorporation. They were obtained by glass powder crystallization; Qss crystals exhibit compositionally tunable coefficients of thermal expansion (CTEs), from − 2 × 10−6 K−1 to ∼10 × 10−6 K−1 in the range 30–300 °C. Co2+-bearing crystals exhibit the closest-to-zero CTE value (0.2 ×10−6 K−1) and the most isotropic behavior in the whole Qss family, opening up new perspectives for the development of Li-free low-expansion materials. From a structural point of view, we identified the unit cell volume (and not the pseudo-hexagonality of the aluminosilicate framework) as the key structural parameter leading to low or negative CTEs in Qss, with a linear correlation extending to non-stuffed non-silicate quartz-like phases.

Substrate Effect on the Thermal Expansion of 2D Materials: An Investigation by Machine Learning Interatomic Potentials

The thermal expansion coefficient (TEC) of suspended two-dimensional (2D) nanomaterials is usually negative due to their ability for large out-of-plane deflection as the temperature increases. The presence of a substrate can nonetheless restrict the flexibility of 2D materials and significantly change their dimensional change by temperature. In this short communication, the thermal expansion coefficients of suspended and supported four popular 2D structures of graphene, phagraphene, C3N and BC3 monolayers is systematically investigated. For this purpose, we conduct molecular dynamics simulation, in which the atomic interactions are defined by highly accurate machine learning interatomic potentials. The obtained results show that by increasing the strength of the van der Waals interactions between the monolayer and the substrate, from 2 meV to 8 meV, the TEC for graphene and phagraphene increases from a negative value to a positive one; while the negative value for the C3N and BC3 structures is still retained. Analysis of molecular dynamics trajectories reveals that the substrate can significantly reduce the formation of out-of-plane wrinkles and consequently affect the value of TEC. The obtained results provide useful vision on the role of substrate on the complex thermal expansion responses of 2D materials.

Recycled soda lime silica glass inclusion in polytetrafluoroethylene matrix as reinforcement for microwave substrate application

AbstractRecycled soda lime silica glass‐filled polytetrafluoroethylene composites were prepared for substrate application at microwave frequencies. Various volume fractions (0.05–0.25) of the filler were dispersed in the polytetrafluoroethylene matrix. The composites’ dielectric, mechanical, and thermal properties were examined with respect to the filler content. X‐ray diffraction data established the phase structure of the polytetrafluoroethylene matrix and recycled soda lime silica glass. Scanning electron microscope micrographs revealed uniform filler distribution at lower recycled soda lime silica contents, while energy dispersive x‐ray analysis showed the purity of the composites. The tensile strength of the composites reduced from 13.5 MPa to 4.26 MPa, while the moisture absorption and density raised from 0.07 % and 2.195 g/cm3 to 0.19 % and 2.228 g/cm3 when the recycled soda lime silica filler volume fraction was adjusted from 0.05–0.25. The lowest coefficient of thermal expansion values was recorded at 0.25 % recycled soda lime silica volume fraction, which increased from 31.12 ppm/°C to 68.32 ppm/°C at 40 °C to 200 °C. At 0.05 filler volume fraction, the respective values of , and of the composites decreased from 2.20, 0.0017, and 29.69 ps to 2.15, 0.0015, and 29.35 ps in the 8.2 GHz–12.4 GHz range.

Effect of Fe-Doping on Thermal Expansion and Stability of Bismuth Magnesium Tantalate Pyrochlorere.

A continuous series of solid solutions (Bi1.5Mg0.75-xFexTa1.5O7±Δ (x = 0-0.75)) with the pyrochlore structure were synthesized with the solid-phase method. It was shown that iron, like magnesium, is concentrated in the structure in the octahedral position of tantalum. Doping with iron atoms led to an increase in the upper limit of the thermal stability interval of magnesium-containing pyrochlore from 1050 °C (x = 0) up to a temperature of 1140 °C (x = 1). The unit cell constant a and thermal expansion coefficient (TEC) increase uniformly slightly from 10.5018 Å up to 10.5761 Å and from 3.6 up to 9.3 × 10-6 °C-1 in the temperature range 30-1100 °C. The effect of iron(III) ions on the thermal stability and thermal expansion of solid solutions was revealed. It has been established that the thermal stability of iron-containing solid solutions correlates with the unit cell parameter, and the lower the parameter, the more stable the compound. The TEC value, on the contrary, is inversely proportional to the cell constant.

Carboxylated Carbon Nanotube/Polyimide Films with Low Thermal Expansion Coefficient and Excellent Mechanical Properties.

Polyimide (PI) films with excellent heat resistance and outstanding mechanical properties have been widely researched in microelectronics and aerospace fields. However, most PI films can only be used under ordinary conditions due to their instability of dimension. The fabrication of multifunctional PI films for harsh conditions is still a challenge. Herein, flexible, low coefficient of thermal expansion (CTE) and improved mechanical properties films modified by carboxylated carbon nanotube (C-CNT) were fabricated. Acid treatment was adapted to adjust the surface characteristics by using a mixture of concentrated H2SO4/HNO3 solution to introduce carboxyl groups on the surface and improve the interfacial performance between the CNT and matrix. Moreover, different C-CNT concentrations of 0, 1, 3, 5, 7, and 9 wt.% were synthesized to use for the PI film fabrication. The results demonstrated that the 9 wt.% and 5 wt.% C-CNT/PI films possessed the lowest CTE value and the highest mechanical properties. In addition, the thermal stability of the C-CNT/PI films was improved, making them promising applications in precise and harsh environments.

Ekspansi Termal, Oxygen Content, dan Sifat Elektrokimia Oksida SmBa0.5Sr0.5Co2O5+δ (70%) + SDC (30%) Sebagai Katoda SOFC

The thermal properties of the double perovskite SmBa0.5Sr0.5Co2O5+δ (70%) + SDC (30%) have been investigated as potential cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFC). This study also includes the oxygen content and electrochemical performance of long-term tests carried out to evaluate the electrochemical stability. Cathode powder is fabricated by a simple and relatively inexpensive solid-state reaction. Oxygen content decreased gradually from room temperature to 800oC by 18.3%. Doping 30% SDC into SBSC oxide can reduce the thermal expansion coefficients (TEC) value from 19.80 x 10-6 (K-1) to 18.17 x 10-6 (K-1) or a decrease of 8.23%. The activation energy (Ea) identified by the electrochemical impedance spectroscopy (EIS), low field (LF), and high field (HF) techniques were 125.3 kJ mol-1, 60.6 kJ mol-1, and 62.5 kJ mol-1, respectively. The SBSC73|SDC|SBSC73 symmetric cell test for 96 hours at 600oC showed an increase in the average polarization resistance value of 0.30% h-1. The cathode grains are evenly distributed with a size of 2-3 µm and tend to be porous. These results exhibit that SmBa0.5Sr0.5Co2O5+δ (70%) + SDC (30%) is a promising cathode material for IT-SOFCs.

Design and preparation of LiAlSiO4-Al2O3 coating for the oxidation resistance improvement of SiC ceramics

The low coefficient of thermal expansion (CTE) coating was designed for SiC oxidation-resistant applications by using Al2O3 and LiAlSiO4 as positive and negative expansion materials. The CTE value, relative density and flexural strength of LiAlSiO4-Al2O3 coating were characterized. The effect of LiAlSiO4-Al2O3 coating on the oxidation resistance and flexural strength of SiC substrate was systematically studied by cyclic oxidation tests at 1400 °C. Results showed that LiAlSiO4-Al2O3 coating with 20 wt% LiAlSiO4 exhibited optimal properties, featuring the excellent relative density of 93.14 %, appropriate CTE of 5.815 × 10−6 /°C, and high flexural strength of 56.35 MPa. The weight gain of the SiC with LiAlSiO4-Al2O3 coating was 0.49 % after 100 h of oxidation, much lower than 2.25 % of bare SiC substrate, indicating that LiAlSiO4-Al2O3 coating effectively hindered the diffusion of oxygen and improved the oxidation resistance of SiC substrate. Moreover, the dense coating blunted defects on the SiC substrate surface, which maintained the high strength of the coated SiC after long periods of oxidation.

Microstructural evolution and thermophysical properties of hypereutectic Al-22Si-xNi alloys prepared by sub-rapid solidification

Al-22Si-xNi (x = 0, 5, 10, 15, 20) alloys were prepared by sub-rapid solidification in the present study. Their microstructures were observed and thermophysical properties were tested. Solidification reactions of the alloys changed with the increase of Ni content. Al3Ni compounds with different morphologies were formed in different solidification stages. The eutectic Al3Ni and primary Al3Ni phase assumed fiber-like and fishbone-like, respectively. Al3Ni–Si binary eutectic structure appeared when Ni content reached 15wt.%. After annealing, the eutectic phase was spheroidized and coarsened. The thermal conductivity decreased with the increasing Ni content. Annealing could enhance the thermal conductivity of the alloys. With the increase of Ni content, the thermal expansion coefficient of the alloys decreased linearly. The as-annealed Al–22Si–15Ni alloy had good comprehensive performance in thermal properties, i.e., the thermal conductivity at 25 °C was 107.09W/(m·K) and coefficient of thermal expansion at 100 °C was 13.04 × 10−6/K. The predicted linear coefficient of thermal expansion values by Turner model agreed well with the experimental values.

Stress Analysis of KDP Single Crystals Caused by Thermal Expansion Mismatch during Traditional Growth

To further elucidate the relationship between the growth stress and cracking of KDP (KH2PO4, potassium dihydrogen phosphate) crystals of different sizes, a three-dimensional finite element calculation was conducted to analyze the growth stress of KDP single crystals grown from Z-plate seeds with varying cooling rates. The mismatch in the coefficient of thermal expansion (CTE), between the cap region and its close vicinity, and among the transparent region, was taken into account. The results indicate that when the cap region is a solid region (when the seed was regenerated with a cooling rate of 0.1 °C/day), the difference in material properties between the cap region and its close vicinity, especially the CTE mismatch along the a-axis, is the main reason of the high stresses. When the cap region is a box-like structure filled with solution (when the seed was regenerated with a cooling rate of 0.3 °C/day), the calculated stress is in proportion to the CTE gradient of the transparent region. Under both models, the stresses induced from an incremental CTE value (from the cap region to the growth front) are greater than those calculated from a diminishing CTE value, implying that the impurities reduce the CTE of KDP crystals, causing the crystals to crack more easily. Despite the maximum stresses inside the crystals changing slightly with an increase in crystal size, the decreased fracture stress of large brittle crystals leads to a higher cracking risk in a large-sized crystal.

Colorless poly(amide‐imide) copolymers for flexible display applications

AbstractColorless polyimide (CPI) films showed great potential for flexible display applications due to their unique combination of excellent optical transparency, and outstanding thermal and mechanical properties. Herein, a series of colorless poly(amide‐imide)s were prepared via a conventional two‐step method, using 1,2,3,4‐cyclobutanetetracarboxylic dianhydride (CBDA), 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 2,2′‐bis(trifluoromethyl)benzidine (TFMB), and 4,4′‐diaminobenzanilide (DABA) as the monomers. The thermal, mechanical, and optical properties of these copolymers were optimized by adjusting the molar ratios of these monomers. The amide linkages significantly improved the mechanical properties and dimensional stability of the resultant CPI films due to strong hydrogen bonding interactions. In particular, CPI‐f films with monomer compositions of TFMB (50 mol%), DABA (50 mol%), 6FDA (50 mol%), and CBDA (50 mol%) exhibited tensile strength of 177 MPa, modulus of 5.5 GPa, coefficient of thermal expansion value of 18 ppm K−1, and glass transition temperature of 394°C. Furthermore, the optical properties of these copolymers were well balanced due to the adoption of CBDA, which can suppress the formation of charge transfer complexes. Specifically, these CPI films displayed transmittance at 550 nm of >88%, b* values of <5.5, haze values of <1%. The aforementioned results revealed that copolymerization is an effective strategy to achieve CPIs with excellent comprehensive properties.