MPa In Air Research Articles

Структура та властивості нових підшипникових композитів на основі сталевих відходів для важких умов експлуатації друкарських машин

The article presents the research results on the structure and properties of new self-lubricating bearing composites based on grinding wastes of high-alloyed steel 8X4V2MFS2 with additives of CaF2 solid lubricant. The new composites are designed to operate in friction units of printing machines at rotational speeds of 600˗800 rpm and increased loads of up to 3.0 MPa. It is shown that the application of the developed technology ensures the formation of a fine-grained heterophase structure of the new composite. The formed structure is a metal matrix base made of regenerated grinding waste from 8X4V2MFS2 steel, consisting of a high-alloy α-solid solution and solid grains of alloying elements’ carbides, as well as a uniformly distributed solid lubricant CaF2. This structure ensured the formation of the new composite’s physical, mechanical and tribological properties high level. In the process of friction, antifriction films were formed on the contact surfaces, which provided a self-lubricating mode. Comparative friction and wear tests have shown significant advantages of the new waste composite compared to cast brass L63, which is traditionally used in friction units of printing equipment. The determined level of physical, mechanical, and tribological characteristics makes it possible to recommend the studied material for use in friction units of printing equipment operating at elevated rotational speeds of 600˗800 rpm and loads up to 3.0 MPa in air. The studies have shown the prospects of using a wide range of valuable metal grinding waste in the repeated production cycle for the manufacture of high-quality composites. The reuse of such waste will make a significant contribution to the protection of the environment from pollution associated with human industrial activity and will help reduce its negative effect on the ecosystem. Keywords: grinding waste, high-alloyed steel, technology, composite bearing, microstructure, solid lubricant, properties, antifriction films, printing machines.

Numerical study on the effect of pillar material on the frequency shift of coupled quartz crystal resonator with pillar

Purpose This paper aims to apply the novel numerical model to analyze the effect of pillar material on the response of compound quartz crystal resonator (QCR) with an array of pillars. The performance of the proposed device compared to conventional QCR method was also investigated. Design/methodology/approach A finite element method model was developed to analyze the behavior of QCR coupled with an array of pillars. The model was composed of an elastic pillar, a solution and a perfectly matched layer. The validation of the model was performed through a comparison between its predictions and previous experimental measurements. Notably, a good agreement was observed between the predicted results and the experimental data. Findings The effect of pillar Young’s modulus on the coupled QCR and pillars with a diameter of 20 µm, a center-to-center spacing of 40 µm and a density of 2,500 kg/m3 was investigated. The results indicate that multiple vibration modes can be obtained based on Young’s modulus. Notably, in the case of the QCR–pillar in air, the second vibration mode occurred at a critical Young’s modulus of 0.2 MPa, whereas the first mode was observed at 3.75 Mpa. The vibration phase analysis revealed phase-veering behavior at the critical Young’s modulus, which resulted in a sudden jump-and-drop frequency shift. In addition, the results show that the critical Young’s modulus is dependent on the surrounding environment of the pillar. For instance, the critical Young’s modulus for the first mode of the pillar is approximately 3.75 Mpa in air, whereas it increases to 6.5 Mpa in water. Originality/value It was concluded that the performance of coupled QCR–pillar devices significantly depends on the pillar material. Therefore, choosing pillar material at critical Young’s modulus can lead to the maximum frequency shift of coupled QCR–pillar devices. The model developed in this work helps the researchers design pillars to achieve maximum frequency shift in their measurements using coupled QCR–pillar.

Synergistic catalysis in loaded PtRu alloy nanoparticles to boost base-free aerobic oxidation of 5-hydroxymethylfurfural

The synergistic catalysis of dual metal sites is vital for selective activation of complicated chemical bonds in biomass compounds. The base-free selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) using air as oxidant and water as solvent is a highly sustainable upgrading process for cellulosic carbohydrates. In this work, a series of PtxRu-MgAlO (x = 0.5, 1, 2 and 3, in mole) nanocatalysts with controlled particle sizes (ca. 2 nm) were synthesized by a PVP-assisted adsorption method. The Pt2Ru-MgAlO catalyst showed 99% selectivity of FDCA with full conversion of HMF at only 100 °C under 0.2 MPa of air. In the meantime, an initial reaction rate of HMF of 2.8 mmol molM−1 s−1 and an intrinsic turnover frequency of 61.5 h−1 were attained, respectively. Besides, this catalyst exhibited superior stability during five consecutive reuses without metal leaching. It was disclosed that the Pt-Ru interaction played critical roles in determining the intrinsic activity and the CO bond activation of the prepared PtxRu-MgAlO catalysts. Kinetic experiments combined with in situ chemisorption techniques clearly unraveled adsorption and activation processes of CO bond on Pt0-Ru0 sites. To the best of our knowledge, this work firstly reported a PtRu bimetallic catalyst for aerobic oxidation of HMF and provided insight into synergistic catalysis.

Graphene with KI-modified pore structure and its electrochemical capacitors application

AbstractThe use of electrochemical capacitors is greatly limited by their poor volumetric energy density, and the key for improving it is to develop porous yet compact carbon materials. In recent years, the densification of porous carbons by capillary forces during drying has been used as a main method to balance the density and porosity of porous carbons for high volumetric performance. But there are still deficiencies in fine tuning the pore structure, which limits the compatibility of porous carbons with high-voltage ionic liquids. We report a KI-assisted method to prepare graphene-based porous carbons with high density and high capacitance. During the synthesis of the carbons, graphene oxide was dispersed in KI solutions with concentrations of 12.5-37.5 mmol/mL followed by hydrothermal treatment at 180 °C for 6 h. The obtained hydrogels were dried in 0.01 MPa of air at 60 °C for 72 h. By this procedure, KI was loaded into a matrix of compact graphene and formed crystals to suppress over shrinkage of pores during drying to produce densification and pseudo-capacitance. Electrochemical characterization of the resulting materials indicated that the ion-accessible surface area and pseudo-capacitance of the porous carbons were increased. The KI/graphene composite with an optimum concentration of KI of 25 mmol/mL achieved both a high electrode density of 0.96 g cm-3 and a high volumetric capacitance of 115 F cm-3 (at 1 A g-1) in an ionic liquid electrolyte (1-alkyl-3-methylimidazolium tetrafluoroborate). A symmetric cell assembled using this material had a high volumetric energy density of 19.6 Wh L-1.

Study on Corrosion Fatigue Properties of the Welded Joints of SMA490BW Weathering Steel

The polarization curve test and corrosion fatigue test of SMA490BW weathering steel welded joints for high-speed train bogies were carried out by electrochemical workstation and fatigue testing machine, respectively, and the fatigue fractures were observed and analyzed by scanning electron microscope (SEM). The results show that: The mechanical properties of the SMA490BW weathering steel welded joints welded by MAG welding are good, the tensile strength is 519MPa, and the elongation after fracture is 26.67%. In 3.5wt% sodium chloride solution, the self-corrosion potential of the heat-affected zone is the lowest, the self-corrosion current density is the largest, and the corrosion resistance is the worst, the weld is in the middle, and the base metal is the best. The corrosion fatigue limit of SMA490BW weathering steel welded joints in 3.5wt% sodium chloride (NaCl) solution is 236.55MPa, which is much lower than the fatigue limit of 335.22MPa in air. SEM fracture analysis showed that the fatigue cracks of the joints in the air originated from the weld pores, while the corrosion fatigue cracks originated from the pitting pits on the surface of the specimens.

Polysilazane-based high-temperature adhesives for the joints of amorphous SiBON ceramic composites

Amorphous SiBON ceramic integrated the advantages of SiO2 and BN can be used as heat-resistant wave transparent composites in radome, and corrosive-resistant high strength materials in aeronautics and astronautics, while it is a great challenge to bind the amorphous SiBON ceramic to solve the problem on difficulty of fabrication of large-sized. In this work, we prepared four kinds of polysilazane-based high-temperature adhesives to join amorphous SiBON ceramic. The joining strength was tested and compared after heat treatment at temperatures ranging from 200 °C to 1100 °C at different atmospheres. Satisfactory shearing strength and toughness (the strength of joints could reach above 25 MPa in air until breakage of ceramic substrate and maximum strength of joints was above 7.5 MPa in Ar) were achieved at the binding interface without pressure applied during joining. The mechanism for the interfacial binding was proposed by analyzing microstructure and chemical compositions. A normal B2O3-SiO2-ZrO2 glass-ceramic interlayer was formed in the joint seam in air, and amorphous SiCN and C3N4 ceramics were generated in the sample in Ar, which reinforced the binding strength of the lap amorphous SiBON ceramic. It is significant to find modified heat-resistant organic adhesives for binding amorphous ceramics to produce high strength ceramic joints in both air and inert atmospheres to resolve the problems on poor processing performance difficulty of fabrication of large-sized of ceramics.

Mild Oxidation of Toluene to Benzaldehyde by Air

We report here the green oxidation of toluene to benzaldehyde by air under mild conditions in >99% selectivity at 35% conversion at 180 °C. This is an important reaction in both theoretical and practical research studies, but little progress has been made in the past five decades. Either the selectivity or the conversion is very low, and the sum of selectivity and conversion is hardly more than one hundred. In previous investigation, we have constructed a highly efficient system of catalysis, i.e., Pickering-like emulsion of toluene in water stabilized by amphiphilic catalysts HDPA-FeOx/Al2O3, hexadecyl phosphonic acid-modulated iron oxides, which work in an enzyme-like mechanism for oxidation of toluene to benzaldehyde. However, the oxygen pressures more than 3 MPa needed for high conversion impede their practical uses. In this work, we modify the catalytic system for the green oxidation of toluene to benzaldehyde using 1 MPa of air as an oxidant. First, the catalytic center of HDPA-FeOx/Al2O3 is optimized as PPA-CuFeOx/Al2O3 with promoted activity of crystal oxygen toward toluene oxidation. Readily available phenylphosphonic acid (PPA), in place of HDPA, shows good performance in the new catalytic system. Second, 5 vol % acetone/water is used as a mixed solvent of the reaction, which markedly modifies the oxygen dissolving and transferring, the access of the toluene molecule to the catalyst, and the recovery rate of catalytic center. The acetone molecule itself, however, is proved not converted and can be recycled in the catalytic process. Comprehensively, the catalytic system including multifactor synergism and good intrinsic safety developed in the current work has realistic feasibility for benzaldehyde production from toluene green oxidation in high-performance and atomic economy.

Tribosynthesis of friction films and their influence on the functional properties of copper-based antifriction composites for printing machines

Abstract This article is devoted to research of the tribosynthesis mechanism of antifriction films and their influence on the functional properties of antifriction composites based on copper alloyed with nickel and molybdenum with the CaF2 solid lubricant additions for operation at rotation speeds of 3,000–7,000 rph and increased loads of 3.0–5.0 MPa in air. Studies have shown that antifriction films are complex, dynamically changing formations on the surfaces of the composite and counterface, developing according to the bifurcation mechanism. The antifriction layer is decisive in the formation of the friction pair's tribological high-level properties, which provide the self-lubrication mode of the friction unit. The formation and permanent presence of the anti-seize film is associated with a balanced wear rate of the film and its constant formation again on these worn areas at rotation speeds of up to 7,000 rph and loads of up to 5.0 MPa. Due to the steady self-lubrication mechanism, the copper-based composite has significant advantages over cast bronze CuSn5ZnPb, which can only work with liquid lubrication in the friction units of printing machines. The performed studies make it possible to choose rational modes for operation of new high-speed antifriction Cu-composites based on the friction films analysis, predicting their high functional properties.

Paste Containing 1.5 μm Ag Particles with Enhanced Surface Area: Ultrafast Thermo-Compression Sinter-Bonding and Annealing Effects

To rapidly sinter a bondline and obtain mechanical stability at high temperature and high thermal conductivity, 1.5 μm Ag particles with enhanced surface area were synthesized by a wet-chemical method, and a sinter-bonding paste containing these Ag particles was obtained. Some particles were present in the form of agglomerates of spike stems and short-branch dendrites, while others existed as spheres with rough nodule surfaces or relatively smooth surfaces. To determine an effective sinter-bonding process, a significantly short thermo-compression bonding (10 s) under 5 MPa in air and subsequent annealing in nitrogen were performed. The thermo-compression bonding at 250 oC resulted in a low shear strength of 8.15 MPa in the formed bondline. Although the annealing at 250 oC increased its strength, it did not reach 20 MPa, which is required for practical applications. Interestingly, the 10 s bonding at 300 oC exhibited sufficient shear strength of 21.96 MPa, and when annealed for 30 min at 300 oC, the excellent strength of 37.75 MPa was obtained. The bondline porosity of 12.16% immediately after the thermo-compression bonding, decreased to 9.13% after annealing for 30 min. The densification in bondline by the annealing also induced a change in the fracture path as well as enhancement in the shear strength. Thus, the suggested subsequent annealing is an effective method for sinter-bonding, similar to the pressureless sinter-bonding process. Consequently, the synthesized Ag particles exhibited superior sintering properties and the suggested combination process shows potential for tremendously improving chip sinter-bonding productivity.

Influence of Glucose on Corrosion Fatigue and Cytocompatibility of Mg–Zn–Zr–Y Alloy

This article mainly focuses on the effects of glucose on the mechanical safety and cytotoxicity of Mg alloys used as implant materials. Under the corrosive human body fluid and dynamic loading, especially in a high‐glucose environment, Mg alloys are inevitably subjected to the decrease of mechanical properties in the process of long‐time service and eventually faced with corrosion fatigue (CF) failure. Herein, a comparative study on the dynamic mechanical properties of the Mg–Zn–Zr–Y alloy is evaluated by carrying out fatigue tests in air and in Hank's solution. CF and cytocompatibility of Mg–Zn–Zr–Y alloys response to different glucose contents (1 and 3 g L−1) are also detected. The Mg–Zn–Zr–Y alloy exhibits an excellent fatigue limit of 119.43 MPa in air compared with 47.77 MPa in Hank's solution at 37 °C. The fatigue cracks initiate at the microstructural defects in air and nucleate at corrosion pits in Hank's solution. Better corrosion resistance and enhanced CF are obtained with the increasing glucose content in Hank's solution. The in vitro tests with MC3T3‐E1 cells demonstrate that the Mg–Zn–Zr–Y alloy shows excellent cytocompatibility under high‐glucose condition.

Creep-Induced Phase Instability and Microstructure Evolution of a Nearly Lamellar Ti–45Al–8.5Nb–(W, B, Y) Alloy

Microstructure degradation and stress-induced transformation of a high Nb-containing TiAl alloy with nearly lamellar microstructure during creep were investigated. Tensile creep experiments were performed at 800, 850 and 900 °C under 150 MPa in air. Microstructures before and after creep tests were examined using scanning and transmission electron microscopy (SEM and TEM). Dislocations within the lamellar structure and βo(ω) region and twin intersection in massive γ grains were investigated. Dislocation sliding played a critical role in the deformation of ωo phase, which preferentially occurred on the (0002)ωo plane. Possible deformation mechanisms were revealed. A stress-induced γ → α2 phase transformation took place during the creep test at 850 and 900 °C. α2 lamella could directly decompose into the ωo phase at 850 °C. The instability of high-temperature microstructure can weaken the creep resistance and promote the plastic deformation of the lamellar matrix, thus could be detrimental to the creep properties. The correlations between creep properties and microstructure instability were discussed.

Fatigue of a SiC/SiC ceramic composite with an ytterbium‐disilicate environmental barrier coating at elevated temperature*

AbstractTension‐tension fatigue performance of a SiC/SiC composite with an ytterbium‐disilicate environmental barrier coating (EBC) was investigated at 1200°C in air and steam. The composite is reinforced with Hi‐Nicalon™ SiC fibers and has a melt‐infiltrated matrix processed by chemical vapor infiltration of SiC with subsequent infiltration with SiC particulate slurry and molten silicon. The EBC consists of a Si bond coat and an Yb2Si2O7 top coat applied via air plasma spraying. Tensile properties were evaluated at 1200°C. Tension‐tension fatigue was examined for maximum stresses of 110‐140 MPa. To assess the efficacy of EBC, experimental results obtained for the coated composite are compared to those for a control uncoated composite. Surface grit‐blasting inherent in the EBC application process degrades tensile strength of the composite. However, the EBC effectively protects the composite from oxidation embrittlement during cyclic loading in air or steam. Fatigue runout set to 200 000 cycles (55.6 hours at a frequency of 1.0 Hz) was achieved at 110 MPa in air and steam. Retained properties of pre‐fatigued specimens were characterized. Composite microstructure, along with damage and failure mechanisms were investigated. Damage and failure of the composite are attributed to the growth of cracks originating from numerous processing defects in the composite interior.

The effect of microstructure on porosity healing mechanism of powder near-β titanium alloys under hot isostatic pressing in α + β-region: Ti-10V-2Fe-3Al

Abstract The relation between phase and structural changes and porosity healing that occurred during hot isostatic pressing (HIP) in the near-β Ti-10V-2Fe-3Al alloy obtained by powder metallurgy was studied. The powders were pressed at room temperature at 750 MPa in air, and then sintered at 1250 °C in vacuum. The residual porosity did not exceed 4.1 vol%. After sintering the HIP treatment was carried out in an argon atmosphere without a container. At the optimal HIP regimes (750 °С, 200 MPa), at which the porosity was completely healed, the structure transformed into the α + β-lamellar type of basket weaving. The dislocation density after HIP treatment mainly increased in the interphase boundaries due to the action of hydrostatic stresses. Nucleation and growth of the secondary α-phase occurs during HIP on the ω-phase particles inside the β-phase. It is shown that the main mechanism of porosity healing in the Ti-10V-2Fe-3Al alloy during HIP is the diffusion of vacancies along cores of the dislocations accumulated at the interphase boundaries. The plasticity of the alloy after HIP increased 2.5 times compared to the state after sintering. It was found out that the mechanism of tensile deformation after HIP, as well as after sintering, is controlled by the α-phase.

Creep in interlaminar shear of an Hi-Nicalon™/SiC–B4C composite at 1300℃ in air and in steam

Creep behavior in interlaminar shear of an advanced SiC/SiC composite with a self-healing matrix was investigated at 1300℃ in laboratory air and in steam. The composite was processed via chemical vapor infiltration (CVI). The composite has a self-healing oxidation-inhibited matrix comprising alternating layers of silicon carbide and boron carbide and is reinforced with laminated woven Hi-Nicalon™ fibers. Fiber preforms were coated with pyrolytic carbon followed by a boron carbon overlay. The interlaminar shear properties were evaluated at 1300℃. The creep behavior was examined for interlaminar shear stresses ranging from 13 to 20 MPa in air and in steam. Primary and secondary creep regimes were observed in all tests conducted in air and in steam. Creep run-out (defined as 100 h at creep stress) was achieved at 13 MPa in air and in steam. Presence of steam had little influence on creep strain rates and creep lifetimes. However, larger creep strains were accumulated in steam than in air. The retained properties of all specimens that achieved creep run-out were characterized. Composite microstructure and damage and failure mechanisms were investigated.

Tribotechnical Properties of Composite Materials Produced from ShKh15SG Steel Grinding Waste

The structure and antifriction properties acquired by a new composite produced from ShKh15SG structural steel grinding waste with additions of CaF2 solid lubricant are examined. The material is intended to operate at 300–400°C under loads of 5.0–7.0 MPa in air. Analysis of the secondary structures and antifriction properties shows that contact surfaces of the test material and counterface are covered with continuous antiseize friction films in the operating conditions in question. They contain chemical elements of both the composite and the counterface, as well as calcium fluoride. Oxygen is also present in the friction films as it participates in their development, entering into chemical reactions with the contacting elements to form various oxides and promote oxidative wear. The antifriction ShKh15SG + 5.0–7.0% CaF2 composite can be effectively used in friction units intended to operate in self-lubrication conditions at 300–400°C under loads of 5.0–7.0 MPa in air. In these operating conditions, the wear rate of the self-lubricating films that form on friction surfaces is balanced by their recovery rate. This is confirmed by high tribological properties. Recovered industrial grinding waste of structural steels is shown to be promising as a metal matrix to make high-quality antifriction composites for specific operating conditions. The structure and properties of the composites can be controlled by choosing the chemical composition of grinding waste and applying optimized manufacturing modes.

Static fatigue of Hi‐Nicalon™‐S fiber at elevated temperature in air, steam, and silicic acid‐saturated steam

AbstractA facility for testing SiC fiber tows in static fatigue and creep at elevated temperatures in air and steam was developed. Static fatigue of Hi‐Nicalon™‐S fibers was investigated at 800°C‐1100°C at applied stresses between 115 and 1250 MPa in air, in Si(OH)4(g)‐saturated steam, and in unsaturated steam. Fibers tested in Si(OH)4(g)‐saturated steam and in air had silica scales throughout the test sections, but those tested in unsaturated steam did not develop scales near the steam injection point. Fiber lifetimes in static fatigue were shortest in unsaturated steam, intermediate in Si(OH)4(g)‐saturated steam, and longest in air. Failure strains did not exceed 0.3%. Steady‐state strain rates and static fatigue lifetimes are modelled empirically by the Monkman‐Grant relationship. Failure mechanisms are discussed.

Fabrication of Ti3SiC2/SiCp multiport minichannel plates for high-temperature applications

An innovative method for fabricating ceramic multiport minichannel plates (MMP) has been developed. The essence of the method is the combustion synthesis of Ti3SiC2/SiCp ceramic matrix composite using sandwich assembly of titanium metal items, viz. rods and sheets, and tape-cast rubber films filled with SiC particles and TiC additive. The fabrication route consists of hot pressing of starting materials at 100 °C under 60 MPa in air into a single integrated unit followed by heat treatment at 1400 °C in a vacuum hot press furnace under small uniaxial load of 80 N. It is shown that the one-dimensional titanium metal items act as both reactants and channel-forming templates. The MMP prepared by the proposed method contains primarily of 45 vol.% Ti3SiC2 and 44 vol.% SiC, as well 11 vol.% TiSi2 minor component. The material exhibits a composite microstructure consisting of a dense Ti3SiC2-based matrix and SiC particles uniformly embedded in it. The sample contains parallel-aligned hollow cylindrical channels of 0.8 mm in diameter distributed with a center-to-center spacing of 1.3 mm. The volume fracture of the channels is estimated to be about 19%.

Efficient removal of bisphenol A from wastewaters: Catalytic wet air oxidation with Pt catalysts supported on Ce and Ce–Ti mixed oxides

Catalytic wet air oxidation (CWAO) of an aqueous solution of bisphenol A (BPA) was investigated at 160 ℃ and 2.0 MPa of air in a batch reactor. Activity of supported platinum catalysts (2.5 wt%), prepared by wet impregnation, was compared with pure cerium and cerium–titanium oxide catalysts. Supported platinum catalysts showed higher activities in the removal of BPA than pure CeO2, Ce0.8Ti0.2O2 and Ce0.2Ti0.8O2. The oxidation reaction was followed the pseudo-first order rate law and the highest BPA removal, 97% and 95%, was achieved with Pt/CeO2 and Pt/Ce0.8Ti0.2O2 catalysts respectively. The CWAO of BPA aqueous solution was not a surface area specific reaction but the more important factor affecting the activity of studied catalysts was the amount of chemisorbed oxygen of these samples.

Experimental investigation on the optical emission spectroscopy of dielectric barrier discharge plasma actuators at different atmospheric pressures

The experiment of dielectric barrier discharge (DBD) plasma actuator using an asymmetrical electrodes configuration is conducted to investigate optical emission spectroscopy of the plasma discharge at pressures from 0.02 to 0.1 Mpa in air mixed with various concentrations of Ar (0%, 20%, 50%, and 80%). The measurements were performed with a sinusoidal driven DBD having an amplitude of 12 kV and a frequency of 1 kHz. The diffuse DBD discharge images and the optical emission spectra are recorded successfully, and the effects of pressure and concentration of Ar are investigated, respectively. It is found that the emission intensities of air discharge increase with decreasing the pressure but increasing the concentration of Ar to some extent. Especially, when the pressure is lower than 0.04 Mpa or the concentration of Ar is over 50%, the emission intensities increase obviously rapidly. The experimental results indicate that the low pressure environment and the high concentration of Ar are beneficial to improve the performance of the DBD plasma discharge actuators.

Creep of a Nextel™720/alumina ceramic composite containing an array of small holes at 1200°C in air and in steam

AbstractTensile stress‐strain and tensile creep behaviors of an oxide‐oxide composite containing an array of small circular holes were evaluated at 1200°C. The composite consists of Nextel™720 alumina‐mullite fibers in a porous alumina matrix. Test specimens contained an array of 17 holes with 0.5‐mm diameter drilled using a CO2 laser. The presence of holes caused reduction in tensile strength and modulus. Tensile creep tests were conducted at 1200°C in air and in steam at creep stresses ranging from 38 to 140 MPa. Primary, secondary, and tertiary creep regimes were noted in air and in steam. The presence of the laser‐drilled holes accelerates the steady‐state creep rates. Creep run‐out, defined as 100 hours at creep stress, was attained for stress levels <60 MPa in air and for stresses <40 MPa in steam. The presence of the laser‐drilled holes significantly degrades creep resistance of the composite. The retained tensile properties of all specimens that attained run‐out were determined. Composite microstructure was examined; the damage and failure mechanisms were considered. The degradation of tensile properties and creep resistance are attributed to damage caused to composite microstructure by laser drilling.