Longer Etching Time Research Articles

Effect of Surface Treatment and Resin Cement on the Bond Strength of an Advanced Lithium Disilicate.

The aim of the study was to evaluate the effect of surface treatment and resin cement on the bond strength of conventional and advanced lithium disilicates (ALDs). Ceramic slices (2 × 13 × 15 mm) of conventional lithium disilicate (LD) (IPS e.max CAD) and ALD (CEREC Tessera) were sectioned, polished, and divided into 16 groups (n = 10) according to the factors: ceramic, surface treatment, and resin cement (Panavia V5 and Variolink Esthetic DC). Surface treatments consisted of hydrofluoric acid 4.9% etching for 20 seconds (Hf20) or 30 seconds (Hf30), self-etching ceramic primer (Se), and sandblasting (Sb). Then, a resin cement cylinder (Ø = 2.5 mm) was manufactured on each specimen's surface. The specimens were then submitted to a shear bond strength (SBS) test. Surface roughness was evaluated through a contact profilometer, and surface morphology was evaluated under scanning electron microscopy for qualitative analysis. Two-way analysis of variance (ANOVA) was used to analyze the data of SBS and surface roughness. For bond strength, the effects of surface treatment, resin cement, and the interaction were analyzed for each ceramic. For roughness, analyzed factors include ceramic and surface treatment. ANOVA revealed that ceramic (p = 0.047) and surface treatment (p < 0.001) factors affected the bond strength, while the cements performed similarly. Both materials showed adequate bond strength (ALD 19.1 ± 7.7 MPa; LD 17.1 ± 7.9 MPa). Sb protocol showed the lowest mean value (9.6 ± 2.9 MPa) compared with Hf20 (22.0 ± 7.1 MPa), Hf30 (21.7 ± 7.4 MPa), and Se (19.3 ± 6.0 MPa). For both ceramics, the highest performance was obtained after applying Se and Hf20 or Hf30. Therefore, longer etching time is unnecessary. Sb protocol must be avoided.

Influence of rear surface pyramid base microstructure on industrial n-TOPCon solar cell performances

A passivating contact structure composition of a heavily doped polysilicon (poly-Si) and a tunneling silicon oxide plays an important role in high-efficiency n-TOPCon (tunneling oxide passivated contact) solar cell, which remarkably reduces recombination losses at both the crystalline silicon rear surface and metal/Si contact interface. However, it is a great challenge for the passivating contact structure to be effectively formed on a pyramidally textured surface due to the presence of sharp vertices, edges, and valleys. In this work, the rear surface microstructure of the TOPCon solar cells was optimized by adjusting the etching time of rear surface chemical polishing after standard alkali texturization in addition to the performance on industrial TOPCon solar cells. It can be observed that the pyramidal vertices were selectively etched and the square pyramid bases were left after the rear surface polishing by using an etching solution composed of 3.4% KOH and 0.93% additive. Besides, a pyramid base with a smaller edge but a higher height could be achieved by etching a shorter time, leading to a rougher rear surface. It could help to reduce the contact resistivity without passivation degeneration, and also assisted to improve the forming ability of metal fingers in the screen-printing process. The average FF corresponding to 170 s, 230 s, and 300 s etching time conditions were 83.62%, 83.44%, and 83.45%, respectively, which is due to the difference of roughness. While a rougher rear surface resulted in a slight difference in the open circuit voltage Voc and the short circuit current Isc. Finally, 210 mm × 210 mm industrial n-TOPCon solar cells achieved an average efficiency of 24.82% at 170 s rear etching time condition, which was an absolute efficiency improvement of more than 0.05% compared with the other two longer etching times. At the same time, batch validation of more than 10,000 pieces showed similar electrical performance improvements with excellent mass producibility.

Study of Anti-Glare Pattern Forming Process by Glass Etching for Improved Image Quality.

In this paper, the anti-glare characteristics of strengthened glass used in the dashboard of automobiles were improved to enhanced the ability of the driver to read the display. To this end, the glass surface was etched with a solution containing HF as a main component. We adjusted the concentration of the etching solution and the etching time as variables, and the transmittance, gloss, haze value, etc. of the etched glass were measured. On the etched glass surface, an irregular pattern mainly containing dioxonium hexa-fluorosilicate crystal phases was generated, and controlling the pattern could improve the anti-glare characteristics of the glass. With higher concentration of the etching solution and longer etching time, the light transmittance, reflectance, and gloss of the etched glass were accordingly lower, while the haze value increased. We discussed the relationship between these property changes and the surface microstructure, pattern components, and roughness of the etched glass.

Influence of the ball surface texture in the dragging of abrasive particles on micro-abrasion wear tests

In several studies about ball-cratering test, a gap remains: how the ball surface texture influences the dynamic of the particles through the contact? In this paper, the influence of ball surface texture in the dragging of abrasive particles on micro-abrasion tests was studied, and the resulting wear mechanisms have been analyzed. The tests were conducted using TiN coated samples and AISI 52100 steel balls provided with different etching times (20 s, 40 s, and 60 s), which induced different balls' texture and roughness. Normal loads of 0.2 N and 0.5 N have been used, utilizing the same rotational speed. Tree different sizes of diamond particles were used: 1–2 μm, 2–4 μm and 4–6 μm. After testing, the coated samples were analyzed by SEM. The steel ball provided with longer etching time caused a slightly higher abrasive damage on the coated samples, and the balls present some embedded particles on the surface, although less than expected. Otherwise, less etched steel ball induced a less intense wear on the samples, enabling light particle sliding/rolling. In this case, the wear rate increased from 4.6 x 10-4 mm3/N·m to 1.3 x 10-3 mm3/N·m when Sa of the balls’ surface raised from 0.047 ± 0.003 μm to 0.239 ± 0.009 μm. The wear mechanisms involved progressed from rolling abrasive mechanism to grooving abrasive mechanism with the growth of the ball surface roughness and abrasive particles size.

Exfoliation and Defect Control of Two-Dimensional Few-Layer MXene Ti3C2Tx for Electromagnetic Interference Shielding Coatings.

Defect-controlled exfoliation of few-layer transition-metal carbide (f-Ti3C2Tx) MXene was demonstrated by optimizing chemical etching conditions, and electromagnetic interference (EMI) shielding coatings were explored. The structural features such as layer morphology, lateral size, layer thickness, defect density, and mechanical stability of the exfoliated f-Ti3C2Tx were strongly dependent on exfoliation conditions. By selecting appropriate exfoliation conditions, moderate etching time leads to the formation of quality f-Ti3C2Tx with lesser defects, whereas longer etching time can break the layer structure and increase defect density, structural misalignment, and oxidative products of f-Ti3C2Tx. The resultant fabricated free-standing flexible f-Ti3C2Tx films exhibited electrical conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) in the X-band of about 3669 ± 33 S/m and 31.97 dB, respectively, at a thickness of 6 μm. The large discrepancy in EMI SE performance between quality (31.97 dB) and defected (3.164 dB) f-Ti3C2Tx sheets is attributed to interconnections between f-Ti3C2Tx nanolaminates interrupted by defects and oxidative products, influencing EMI attenuation ability. Furthermore, the demonstrated solution-processable high-quality f-Ti3C2Tx inks are compatible and, when applied for EM barrier coating on various substrates, including paper, cellulose fabric, and PTFE membranes, exhibited significant EMI shielding performance. Moreover, controlling defects in f-Ti3C2Tx and assembly of heterogeneous disordered carbon-loaded TiO2-Ti3C2Tx ternary hybrid nanostructures from f-Ti3C2Tx by tuning etching conditions could play an enormous role in energy and environmental applications.

Abfraction: Etiopathogenesis, clinical aspect, and diagnostic-treatment modalities: A review

Abfraction is a loss of tooth structure along the gingival margin and manifests with different clinical appearances. It has multifactorial etiology and may occur due to normal and abnormal tooth function and may also be accompanied by pathological wear, such as abrasion and erosion. The theory behind the abfraction is that the tooth flexure in the cervical area is caused due to occlusal compressive forces and tensile stresses. This results in the fractures in the hydroxyapatite (HA) crystals. It is also caused by the low packing density of the Hunter-Schreger band (HSB) at the cervical area. Unfortunately, there is a lack of evidence regarding the outcome of abfraction with or without intervention. The aim of this review is to collect clinical information from the literature and discuss the etiology, pathogenesis, clinical representation, and management. Also, search databases for clinical studies that describe the role of sclerotic dentine in non-carious cervical lesions (NCCLs) are becoming a clinical challenge. The literature was searched that described the etiology, pathogenesis, clinical representation, and management of the abfraction lesions. Also, a specific question regarding the formation of sclerotic dentin in the NCCL lesion was described and searched for evidence that challenges etching, bonding, and successfully restoring NCCLs. The databases PUBMED, SCOPUS, MEDLINE, WEB of SCIENCE, and EMBASE were searched using the key terms. The inclusion criteria were the randomized controlled clinical trial, cohort studies, and cross-sectional studies that aimed at determining the role of sclerotic dentine in NCCLs and its effect on etching, bonding. One clinical study was retrieved according to the PRISMA flowchart and PICO format. The longer etching time, total-etch adhesive system, and EDTA pre-treatment of the sclerotic dentin of cervical wedge-shaped defects could improve the bonding strength in lesions like NCCL's. In conclusion, clinical challenges that occur due to NCCLs are better managed by a proper understanding of factors like etiopathogenesis, ultra-structure of enamel, and dentine and their effect on the bonding of restorations of the tooth.

Strength of a Zirconia-Reinforced Lithium Silicate Ceramic: Acid-Etching Time and Resin Cement Application Effects.

This study aimed to evaluate the effect of hydrofluoric (HF)-acid-etching time and the impact of a resin-cement layer on the biaxial flexural strength and structural reliability of a zirconia-reinforced lithium silicate (ZLS) glass ceramic. Disc-shaped specimens (n = 15) were divided according to: etching time (conditioning with 10% HF acid for 20, 40, and 60 seconds), and application of a resin-cement layer. Biaxial flexural, contact angle, and roughness analyses were performed. When the resin-cement layer was not present, flexural strength data increased with increasing etching times: 20 seconds = 250.8 MPa; 40 seconds = 278.4 MPa; 60 seconds = 342.9 MPa. Application of resin cement increased the strength values (20 seconds of acid etching on specimens with a resin-cement layer = 341.8 MPa). Different etching times did not affect the roughness of ZLS, and the contact-angle analysis presented lower values for 60 seconds of acid etching. The flexural strength of ZLS was only sensitive to surface changes when less exposure time was conducted. Longer etching times (40 and 60 seconds) should be considered for conditioning ZLS ceramic along with adhesive cementation.

Terahertz Emission of Gallium Arsenide on Textured p-type Silicon (100) Substrates Grown via Molecular Beam Epitaxy

This study presents the terahertz (THz) emission of molecular beam epitaxy (MBE)-grown Gallium Arsenide (GaAs) on surface textured p-type Silicon (p- Si) (100) substrates. Surface texturing was achieved by anisotropic wet chemical etching using 5% wt Potassium Hydroxide (KOH): Isopropyl alcohol (IPA) (50:1) solution for 15, 30, 45, and 60 minutes. Reflectivity measurements for the textured p-Si(100) substrates indicated that the overall texturing increases with longer etching times. Raman spectroscopy of the post-growth samples confirmed GaAs growth. The THz emission intensities were the same order of magnitude. The GaAs grown on p-Si(100) textured for 60 minutes exhibited the most intense THz emission attributed to the increased absorption from a larger surface-to-volume ratio due to surface texturing. All GaAs on textured p-Si(100) samples had frequency bandwidth of ~2.5 THz.

Selective dentin etching: A potential method to improve bonding effectiveness of universal adhesives.

To evaluate whether selective dentin etching protocols using reduced phosphoric acid (H3PO4) etching-times would affect the resin-dentin interaction of a universal adhesive to improve long-term bonding effectiveness. Mid-coronal flat dentin surfaces were produced on sound third molars, selectively etched with 32% H3PO4 for 3, 5, 10 or 15 s and bonded with a universal adhesive (Scotchbond Universal, 3 M ESPE: SU). SU in self-etch mode and a three-step etch-and-rinse adhesive were used as control groups. Bonded specimens were stored in deionized water for 24 h and sectioned into beams (cross sectional area of 0.7 mm2). Micro-tensile bond strength test (n = 6) and nanoleakage evaluation were performed immediately, after thermocycling or 6-month storage in artificial saliva. Energy dispersive X-ray analysis (n = 6) was performed to determine the residual Ca-content ratio at the hybrid layers and scanning electron microscopy (SEM) was used to observe the micromorphology of the etched dentin surfaces before and after SU application. Data were analyzed by ANOVA and Tukey test (α = 0.05). Selective dentin etching for 3 s improved the interaction depth of the tested universal adhesive without overexposing demineralized collagen or reducing Ca-content availability at the bonded interface. The improved immediate bond strengths of the selective etching protocol remained significantly higher (p < 0.05) after long-term aging producing hybrid layers without significant differences (p > 0.05) in silver uptake levels compared to those produced on non-etched dentin. Despite the adjunctive conclusion that universal adhesives used in self-etch mode produce superior long-term dentin bonding compared to the etch-and-rinse mode, selective etching for 3 s with conventionally used H3PO4 improves dentin bonding effectiveness; nonetheless, longer etching times should be strictly avoided.

EFFECT OF ETCHING AS PRE-TREATMENT FOR ELECTROLESS COPPER PLATING ON SILICON WAFER

Metallic coatings, such as copper films can be easily deposited on semiconductor materials like silicon wafer without prior surface pre-treatment using the electroless process. However, the adhesion of the copper film can be very weak and can easily peels off. In this study, the effect of etching in hydrofluoric acid solution as a surface pre-treatment prior to electroless plating on silicon wafer was studied. The etching time in hydrofluoric acid was varied at 1, 3 and 5 minutes in order to investigate the adhesion behaviour of the coating layer. The surface morphology of the electroless plated samples was observed using a field emission scanning electron microscope (FESEM) and the coating thickness was measured using cross sectional analysis. The results showed that longer etching time (5 minutes) produced thicker Cu deposits (8.5μm) than 1 minute etching time (5μm). In addition, by increasing the etching time, the mechanical bonding between the copper film and the substrate is improved.

Effect of Hydrofluoric Acid Etching Time on Titanium Topography, Chemistry, Wettability, and Cell Adhesion.

Titanium implant surface etching has proven an effective method to enhance cell attachment. Despite the frequent use of hydrofluoric (HF) acid, many questions remain unresolved, including the optimal etching time and its effect on surface and biological properties. The objective of this study was to investigate the effect of HF acid etching time on Ti topography, surface chemistry, wettability, and cell adhesion. These data are useful to design improved acid treatment and obtain an improved cell response. The surface topography, chemistry, dynamic wetting, and cell adhesiveness of polished Ti surfaces were evaluated after treatment with HF acid solution for 0, 2; 3, 5, 7, or 10 min, revealing a time-dependent effect of HF acid on their topography, chemistry, and wetting. Roughness and wetting increased with longer etching time except at 10 min, when roughness increased but wetness decreased. Skewness became negative after etching and kurtosis tended to 3 with longer etching time. Highest cell adhesion was achieved after 5–7 min of etching time. Wetting and cell adhesion were reduced on the highly rough surfaces obtained after 10-min etching time.

The Impact of Different Acids Etch on Sandblasted Titanium Dental Implant Surfaces Topography

Purpose: The study was conducted to evaluate the effect etching with different types of acids on sandblasted titanium dental implant surface topography. Materials and Methods: Pure polished titanium discs were blasted with Aluminum oxide powder (Al2O3) with particle size 50 μm using 4.5 bar pressure. Then the blasted discs were etched using different acids solutions separately for 5 min, 15 min, 30 min. Surface roughness was measured using profilometry. Topography was examined using scanning electron microscopy (SEM). Results: The morphology and the surface roughness of titanium discs was changed dramatically after blasting with alumina, a rough surface was visible to the naked eye with Ra value of 0.627 μm. A steep increase in surface roughness (Ra value) of alumina blasted/acid etched surfaces were noticed for all acid types immediately after the start of etching. The increase in Ra was more than 0.2 μm for all acid types. Slight changes in Ra value were observed with longer etching times. Conclusions: This work shows that surface roughness using blasting procedure depended upon type and particle size of used material and original surface roughness of the substrate. Etching blasted surface with different types of acids produce different surface topography and different roughness, and a slight difference in duration have significant impact on titanium surface topography. Key word: Dental implant, titanium, surface modification, sandblast, acid etch.

Enhanced Capacitive Performance Based on Diverse Layered Structure of Two-Dimensional Ti3C2 MXene with Long Etching Time

Two-dimensional Ti3C2 MXene nanosheets were synthesized by selective etching of Al layer from ternary carbides Ti3AlC2 MAX phase using HF solution for different etching times and then evaluated as working electrodes. The effects of the etching time on the morphology, structure, surface termination, and electrochemical properties of Ti3C2 MXene were investigated. With longer etching time, Ti3C2 nanosheets were gradually delaminated and more C was exposed. The electrochemical properties of Ti3C2 show a significant improvement at the reaction time of 216 h (Ti3C2-216), with no obvious changes with etching time from 2 to 168 h. Ti3C2-216 exhibited higher capacitive performance with the specific capacitance of 118 F g−1 at the scan rate of 5 mV s−1, excellent rate performance, and cycling stability. This improvement in the performance is attributed to higher carbon content for better conductivity and faster transportation of electrons, and the larger specific surface area for more access of aqueous electrolyte to the electrodes.

In-Situ Fabrication of a Self-Aligned Selective Emitter Silicon Solar Cell Using the Gold Top Contacts To Facilitate the Synthesis of a Nanostructured Black Silicon Antireflective Layer Instead of an External Metal Nanoparticle Catalyst.

Silicon solar cells with nanopore-type black silicon (b-Si) antireflection (AR) layers and self-aligned selective emitter (SE) are reported in which the b-Si structure is prepared without the traditional addition of a nanoparticle (NP) catalyst. The contact-assisted chemical etching (CACE) method is reported here for the first time, in which the metal top contacts on silicon solar cell surfaces function as the catalysts for b-Si fabrication and the whole etching process can be done in minutes at room temperature. The CACE method is based on the metal-assisted chemical etching (MACE) solution but without or metal precursor in the Si etchant (HF:H2O2:H2O), and the Au top contacts, or catalysts, are not removed from the solar cell surface after the etching. The effects of etching time, HF and H2O2 concentration, and the HF:H2O2 ratio on the b-Si morphology, surface reflectivity, and solar cell efficiency have been investigated. Higher [HF] and [H2O2] with longer etching time cause collapse of the b-Si nanoporous structure and penetration of the p-n junctions, which are detrimental to the solar cell efficiency. The b-Si solar cell fabricated with the HF:H2O2:H2O volume ratio of 3:3:20 and a 3 min etch time shows the highest efficiency 8.99% along with a decrease of reflectivity from 36.1% to 12.6% compared to that of the nonetched Si solar cell.

The effects of substrate roughness and associated surface properties on the biocompatibility of diamond-like carbon films

Diamond-like carbon (DLC) films have many excellent properties such as high hardness, low friction coefficient, chemical inertness, and biocompatibility. Their good biocompatibility is a result of their chemical composition containing only carbon and hydrogen which are biologically compatible. Previous studies on biocompatibility of DLC films focus primarily on morphological issues like roughness and wettability. However, we believe that the stress and the associated surface properties in the films are equally important. In exploring these effects, the silicon substrates were roughened with 30wt.% KOH in different etching time. The substrate roughness was increased by longer etching time. Three different types of samples – silicon without DLC film, smooth silicon with DLC thin film and rough silicon with DLC – were prepared by culturing the human endothelial cell ECV304 for 72h. The DLC films were examined by AFM, Raman spectroscopy, XPS, sessile drop and surfcorder to study the morphology, chemical bonding, wettability and residual stress. For DLC surface properties, as the substrate roughness increases, the residual stress increases and the sp3/sp2 ratio decreases. Meanwhile, the surface became more hydrophobic. The stress caused by the substrate roughness seems to be correlated with the surface properties of DLC. As for the ECV304 cell culture, the viability for bare silicon without DLC is almost zero. This indicates that silicon is not biocompatible for ECV 304. The cell number of ECV in DLC/rough substrate is less than that in DLC/smooth substrate in a 72-hour cell culture. This implies that a DLC/Si whose surface properties are associated with higher stress is adverse to ECV cell culture.

Fabrication of Silicon Nanowires by Electroless Etching for Thermoelectric Application

The fabrication procedure of silicon nanowire thermoelectric device has been developed based on the electroless etching method. Under a fixed etching solution concentration ratio and the etching reaction temperature, silicon nanowire arrays of different lengths manufactured at different etching time were investigated. The longer etching time results in the longer nanowire length. The silicon nanowire arrays were utilized to produce a silicon nanowire thermoelectric device. The I-V characteristics of the present SiNWs thermoelectric device were recorded under different heating temperatures, and the power outputs of silicon nanowire thermoelectric devices were calculated. The longer the silicon nanowire thermoelectric device lines, the greater the power output of thermoelectric device is. The SiNWs TED power output in the present study ranges from 1.62 to 7.2 nano-Watt with the chip size 2×2 cm2 while the applied temperature at 150 °C.

Comparison of six different methods of cleaning and preparing occlusal fissure surface before placement of pit and fissure sealant: An in vitro study

The purpose of this in vitro study was to evaluate and compare the microleakage of pit and fissure sealants after using six different preparation techniques: (a) brush, (b) pumice slurry application, (c) bur, (d) air polishing, (e) air abrasion, and (f) longer etching time. The study was conducted on 60 caries-free first premolars extracted for orthodontic purpose. These teeth were randomly assigned to six groups of 10 teeth each. Teeth were prepared using one of six occlusal surface treatments prior to placement of Clinpro" 3M ESPE light-cured sealant. The teeth were thermocycled for 500 cycles and stored in 0.9% normal saline. Teeth were sealed apically and coated with nail varnish 1 mm from the margin and stained in 1% methylene blue for 24 hours. Each tooth was divided buccolingually parallel to the long axis of the tooth, yielding two sections per tooth for analysis. The surfaces were scored from 0 to 2 for the extent of microleakage. Results obtained for microleakage were analyzed by using t-tests at sectional level and chi-square test and analysis of variance (ANOVA) at the group level. The results of round bur group were significantly superior when compared to all other groups. The application of air polishing and air abrasion showed better results than pumice slurry, bristle brush, and longer etching time. Round bur group was the most successful cleaning and preparing technique. Air polishing and air abrasion produced significantly less microleakage than traditional pumice slurry, bristle brush, and longer etching time.

Effect of Wet Etching Parameter on the Diameter and Length of Silicon Nanowires

A wet etching method for preparing silicon nanowires on silicon substrates at near room temperature is presented. The effect of experiment parameter on the silver nanoparticle forming including concentration of AgNO3, immersing time and solution temperature, and the effect of etching time on the length of silicon nanowires are investigated. It is concluded that solution temperature has more impact to diameter of silicon nanowires than concentration of AgNO3 and immersing time and longer etching time may result in longer silicon nanowires.

Surface and bulk structural properties of nanostructured porous silicon prepared by electrochemical etching at different etching time

Nanostructured porous silicon (NPSi) is versatile nanomaterials, and attractive area in device application after visible luminescence was observed from NPSi by Canham (1990). NPSi has been prepared by electrochemical techniques with silicon wafer as a based material. The electrolyte solution consists of ethanol and hydrofluoric acid at volume ratio of 1:1. The etching time was varied while other preparation parameters were fixed to produce different porosity of NPSi samples. The structural properties of samples were measured using field emission scanning electron microscope and Raman spectrometer. The surface structural study has shown the surface roughness increase at inertial stage but decrease gradually with longer etching time. However, nanostructured surface was decreased with increasing of etching time. From side view measurement, the nanopillar of NPSi becomes smaller size while increase of etching time. The crystallinity of PSi is observed by Raman scattering varied with different etching time. The photoluminescence measurement will be carried out to study the correlation between optical and structural properties.

Charge resolution of CR-39 plastic nuclear track detectors for intermediate energy heavy ions

The charge resolution ( δZ) for heavy ions (nuclear charge: Z < 40) of 0.1–1 GeV/n energy in CR-39 plastic nuclear track detector (PNTD) and its dependence on etching time, and on projectile Z and energy were investigated and optimized as part of an effort to make precise measurements of projectile charge-changing cross sections. Two types of CR-39 PNTD, HARZLAS TD-1 and BARYOTRAK, were exposed to heavy ion beams with seven values of Z behind thick targets to produce projectile fragments. Following chemical etching (7 N NaOH at 70 °C) for varying etch times, δZ of the projectiles was determined for each detector type. A strong dependence of δZ on the amount of bulk etch ( B) was seen. It was also observed that δZ can be remarkably improved with longer etching time as a function of B −1/2, in accordance with the trend seen in other types of track detector such as glass nuclear track detector. However, for B ⩾ 60 μm (30 h etching), saturation occurs and there is no further improvement in δZ. Analysis of the correlations between projectile Z, energy, detector response, and fluctuation of the response make it possible to develop a model to predict the δZ for projectiles of given Z and energy. The predicted and measured values of δZ show good agreement within 10%. We conclude that 4 ⩽ Z ⩽ 30 at intermediate energy can be identified with good δZ in these detectors. The predictive model will be used in designing future cross section measurement experiments.