Effect Of Soaking Time Research Articles

Effect of Soaking Time on Paste Carburizing of Carburized Low Carbon Steel

Increase of soaking time contributed to the effectiveness of case depth formation, hardness properties and carbon content of carburized steel. This paper investigates the effect of different soaking time (7-9 hours) using powder and paste compound to the carburized steel. Low carbon steels were carburized using powder and paste compound for 7, 8 and 9 hours at temperature 1000°C. The transformation of microstructure and formation carbon rich layer was observed under microscope. The microhardness profiles were analyzed to investigate the length of case depth produced after the carburizing process. The increment of carbon content was considered to find the correlation between types of carburizing compound with time. Results shows that the longer carburized steel was soaked, the higher potential in formation of carbon rich layer, case depth and carbon content, which led to better hardness properties for carburized low carbon steel. Longer soaking time, 9 hours has a higher dispersion of carbon up to 41%-51% compare to 8 hours and 7 hours. By using paste carburizing, it has more potential of carbon atom to merge the microstructure to transform into cementite (1.53 wt% C) compare to powder (0.97 wt% C), which increases the hardness of carburized steel (13% higher).

PENGARUH WAKTU PERENDAMAN DALAM LARUTAN ASAM ASETAT (CH3COOH) TERHADAP KARAKTERISTIK FISIK DAN KIMIA GELATIN CEKER AYAM

ABSTRACTTHE EFFECT OF SOAKING TIME IN ACETIC ACID SOLUTION ON PHYSICAL AND CHEMICAL CHARACTERISTICS OF CHICKEN CLAW GELATIN. This study was conducted to determine the effect of soaking time in acetic acid solution(CH3COOH) on physical and chemical characteristics of chicken claw gelatin. This study used Completely Randomized Design (CRD) the reatments were soaking time (12, 24, 36 and 48 hours) and four replicates of treatment. The result showed that the curing time had no significant effect (P> 0,05) to the gel strength and viscositas of gelatin, but it had significant effect (P<0,05) on rendemen and water content of gelatin. It was concluded that the chicken claw gelatin produced from soaking time 36 hours had the best physical and chemical characteristics. Key words: Acetic acid, Gelatin, Chicken claw

Using combined optimization, GC–MS and analytical technique to analyze the germination effect on phenolics, dietary fibers, minerals and GABA contents of Kodo millet (Paspalum scrobiculatum)

A central composite rotatable design was applied to study the effects of soaking time, germination time and temperature on the responses; total phenolics, total flavonoids and antioxidant activity for the biochemical enhancement of bioactive components of Kodo millet. The optimum conditions for producing germinated Kodo millet flour of highest TPC (83.01mgGAE/100g), TFC (87.53mgRUE/g) and AoxA (91.34%), were soaking time (13.81h), germination temperature (38.75°C) and germination time (35.82h). Protein increased significantly form, 6.7 to 7.9%, dietary fibers from 35.30 to 38.34g/100g, minerals from 232.82 to 251.73mg/100g, GABA contents from 9.36 to 47.43mg/100g, whereas phytates and tannins decreased from 1.344 to 0.997mol/kg and 1.603 to 0.234mg/100g respectively, in optimized germinated Kodo millet sample. Six new bioactive compounds [n-propyl-9,12,15-octadecatrienoate (0.86%), pregan,20-one-2hydroxy,5,6,epox-15-methyl (3.45%), hexa-decanoicacid (8.19%), 9,O-ctadecenoicacid (5.00%), butyl-6,9,12,15-octadecatetraenoate (4.03%), hexadecanoicacid-methylester (1.43%)], synthesized as a result of germination under optimum conditions in the Kodo millet depicted the germination potential of millets as a source of valuable bioactive compounds.

Changes in the antioxidant capacity and phenolic compounds of maesil extract during one-year fermentation.

This study aimed to identify the effects of soaking time and fermentation temperature and period on the total phenolics, total flavonoids, and antioxidant activity of maesil extract. Green maesil fruits were fermented with brown sugar at 15 or 25°C for one year. After soaking maesil for 90 days, the fruits were removed and the remaining liquid was further ripened for 275 days, whereas other samples continued to ferment with maesil until 365 days. Total phenolics, total flavonoids, and antioxidant activities of the extracts fermented with maesil for one year were higher compared with those wherein the fruits were removed at day 90. The total phenolic and total flavonoid contents were relatively higher at 15°C, whereas the ABTS and ferric-reducing antioxidant power (FRAP) activities were significantly higher at 25°C. The total phenolic and total flavonoid contents highly correlated with the antioxidant activities. These results show that fermentation temperature plays a critical role in enhancing the phenolic compounds and antioxidant activity of maesil extract.

Evaluation of Iron and Manganese-coated Pumice from Sungai Pasak, West Sumatera, Indonesia for the Removal of Fe (II) and Mn (II) from Aqueous Solutions

The objective of this study was to evaluate the performances of iron and manganese-coated pumice from Sungai Pasak, West Sumatera, Indonesia as the adsorbents for removal of Fe (II) and Mn (II) from aqueous solutions. The effect of soaking time for iron and manganese coating was evaluated and as comparison, the adsorption of Fe (II) and Mn (II) using uncoated pumice was conducted. The experiments were performed in batch mode at room temperature (20-25̊C), pH 7; 10 g/L of adsorbent dose; 0.30-0.50 mm of adsorbent diameters; 100 rpm of agitation speed and 90 minutes of contact time. In addition, the desorption process of Fe (II) and Mn (II) from the three kinds of adsorbent was also investigated. The results showed that the optimum soaking time for iron and manganese coating for removal of Fe (II) and Mn (II) were 100 and 48 hours, respectively. Iron-coated pumice showed to have high removal efficiencies of two ions compared to uncoated and manganese-coated pumice. More than 84% of Fe(II) and 72% of Mn(II) with initial concentration of 15 and 5 mg/L, respectively, were removed by 10 g/L iron-coated pumice, while by using uncoated and manganese-coated pumice, the removal efficiencies were less than 75% for the two ions. The desorption study noticed that up to 20% of Fe (II) and 100% of Mn (II) were recovered from the three kinds of pumice adsorbent. Overall study indicated that pumice from Sungai Pasak may be a promising adsorbent for iron and manganese removal from water and wastewater.

A comparative experimental study of IOR potential in fractured shale reservoirs by cyclic water and nitrogen gas injection

Oil production from tight and shale formations accounted for more than half of total U.S. oil production in 2015 (EIA, 2016). Such amount is expected to grow significantly as the active development of low permeability reservoirs continues. Since the primary recovery is becoming less effective and large amounts of oil are locked in matrix, IOR techniques should be considered to face such challenge. Many recent studies have evaluated the potential of gas injection in shale plays. However, few studies discussed the feasibility of water huff-n-puff process. This study evaluated the potential of cyclic water injection (CWI) in shale plugs and compared it with the performance of cyclic gas injection (CGI).Eagle Ford core samples were used in this study and saturated with dead shale oil. X-ray diffraction (XRD) technique was employed to analyze the mineral composition of the sample. To reduce clay swelling, 5wt% of potassium chloride (KCl) solution was used as the injection fluid in CWI tests. Two groups of experiments were performed to examine the effects of soaking time and injection pressure (Pin) on the recovery performance. For one cycle of huff-n-puff, after reaching the Pin, the core plug was soaked with water for a certain time, then the surrounding pressure was released to enter the production period. Under the same operating conditions, CGI tests were conducted to compare the two IOR performances.The CWI experimental results show that soaking time affects the recovery factor (RF) of a single cycle within a certain range, which was similarly concluded from the CGI tests. Injection pressure can affect the recovery performance of CWI significantly. For example, after performing 12 cycles of water huff-n-puff, the RF for tests with Pin of 1000psi and 5000psi were 14% and 21%, respectively. When applying 5000psi, fractures were created on the plug and the size enlarged with further cycles operated. Comparing the two processes of CWI and CGI, different recovery characters can be observed. CWI showed the recovery potential at the first four cycles, and then the incremental oil recovery decreased dramatically in the subsequent cycles. By contrast, CGI presented a more continuous and steady recovery performance with high incremental RF, and then gradually diminished after seven cycles of huff-n-puff processes.

The viability of microwave sintering process to produce a ceramic tool insert

Microwave processing of ceramics is fast emerging as a new field of ceramic processing and material synthesis. The past year has witnessed significant progress in the aspects of commercialization and application of the technology in new areas. Due to that reason, several experiments were conducted on microwave heating of ceramics. The aim of the study is to investigate i) whether microwave is a viable alternative to produce sintering parts, ii) the effect of soaking time on the properties of the sample, and iii) the influence of several binders including nickel, ferum, chromium and cobalt to tungsten carbide cermets. The study involved studying the density, hardness and microstructure of the sintered samples. The samples were compacted using an Instron machine at 200 MPa in a cylindrical shape using pallet press with a height of 10 mm and a diameter of 20 mm and sintered in microwave hybrid sintering at 1450°C for two different soaking time (10 min and 20 min). The soaking time of 10 min showed better density, hardness and microstructural results compared to those of 20 min. In comparing between the binders, Ni and Fe (Ni-Fe) showed better results compared to Ni and Cr. While cobalt, nickel and ferum (Co-Ni-Fe) had enhanced results compared to Co and Cr (Co-Cr). Although there are a lot of research studies on several other binders, there is still no finding on the use of microwave hybrid sintering to sinter different mixing binders of tungsten carbide cermets. Therefore, in this research, it is believed that the use of microwave hybrid sintering is viable to sinter tungsten carbide cermets with different binders. The density result showed that each composition of the sintered density was higher compared to green density, which increased by 30% than the green density on average. On the other hand, the hardness results from the commercial cutting tool for tungsten carbide cermet was in the range of 80 to 92 HRA and the highest result for hardness in this research was 84.3 HRA, which means that the insert can be used for commercial use depending on the application

How direct electrospinning in methanol bath affects the physico‐chemical and biological properties of silk fibroin nanofibrous scaffolds

Developing a rapid and easy approach to fabricate crystalline silk fibroin nanofibres without any needs for post-processing stage is focused. Thus, methanol bath was chosen as the collector and then the effect of soaking time on the properties of fibroin fibres was investigated. The results indicated that the wet-electrospun mats had higher fibre diameter than mats made by conventional electrospinning system. With prolonging the electrospinning time in methanol bath, a slight increase in the average fibre diameter and crystallinity were observed. In addition, the stiffness of the wet-electrospun mats increased with increasing soaking time, while the breaking stress decreased. The cellular viability of the osteoblast-like cells (MG63) on fibroin mats improved during wet-electrospinning process, while no significant difference was observed for cell attachment. Accordingly, it seems that wet electrospinning in methanol for 30 min is optimal for bone regeneration on account of viability and mechanical property.

NaOH-Thiourea Aqueous Solution Treatment of Cellulose Fiber and its Effects on Bulk and Softness

Bleached kraft pulp of hardwood was pretreated in a NaOH-thiourea aqueous solution to modify the bulk and softness of the cellulose fibers with minimal reduction in paper strength. The effects of soaking time, fiber concentration, alkali dosage, and freezing time were evaluated through single factor experiments. The optimal conditions were determined to be a soaking time of 15 min, fiber concentration of 15%, alkali dosage of 9%, and freezing time of 75 min. Under the optimal conditions, the bulk and softness of the treated cellulose fibers were increased by 28.7% and 21.6%, respectively, compared with those of untreated cellulose fibers. The tensile and burst indices were only reduced by 1.2% and 5.1%, respectively, under these conditions. Also, there were almost no effects on the polymerization degree, the thermostability, and the structure of the functional groups or crystalline regions.

Testing the effect of soak time on catch damage in a coastal gillnetter and the consequences on processed fish quality

This study aims at testing how to improve catch quality aboard a coastal gillnetter by looking at an easily controllable parameter known to have an effect on the degree of fish damage, soak time, and investigating if the registered damages on whole fish have an effect on processed products such as fillets. Plaice (Pleuronectes platessa) was captured with commercial gillnets soaked for 12 and 24 hours. Damages were assessed using semi-quantitative indices of individual fish condition gathered in a Catch-damage-index for onboard fish and a Processed fish-damage-index for whole, skinned and filleted plaice processed at a land-based factory. Cumulative link mixed modelling allowed the estimation of the size of effects. Damage in fish was significantly more likely for longer soak times but effects were comparable to those of fish length and between-sets, making a change in soak time not so substantial for improving plaice quality in coastal gillnetting. Damage in fish was significantly more likely for whole than filleted fish, but there was substantial heterogeneity among fish. Severe damage in whole fish may not matter in filleted fish whereas some damage may only be visible at the fillet level.

Rapid Biomimetic Coating of Calcium Phosphate on Titanium: Effect of Soaking Time, Temperature and Solution Refreshing

The influence of employing three different solution temperatures (23, 37 and 50 °C), three soaking times (2, 4 and 6 h) and two solution refreshing methods (Refreshed or Non-refreshed) in rapid biomimetic coating process on phase composition, functional groups, coating content and microstructure of the resulted coating was studied. Increasing soaking times and temperature increased the coating content in all cases regardless of the use of refreshed or non-refreshed accelerated calcium phosphate solution. The use of non-refreshed solution resulted in the lower rate of coating than that of refreshed solution at all coating temperatures. However, all coatings similarly comprised octacalcium phosphate and hydroxyapatite as main phases and the microstructure consisted of sharp and interconnected plate-like crystals vertically grown on the surface of titanium. However, two types of crystal structure were produced. Low solution temperature resulted in isolated spheroids while uniform and distributed crystal structure was produced by using high solution temperature. This could be related to the difference in nucleation and precipitation rate formed in rapid biomimetic coating process as a result of the interplay between temperature and ionic strength of the solutions.

Evaluating the effect of soak time on bottomfish abundance and length data from stereo-video surveys

Baited stereo-camera surveys of fish assemblages provide conservative estimates of abundance and length-frequency distributions. While underwater camera systems have numerous advantages over traditional fishing and diver surveys, limitations in sampling capacity, data processing time, and resultant data still exist. Previous studies have shown that shorter camera soak times can increase sampling efficiency and reduce per-sample data processing time without affecting overall data quality. Using data from stereo-video surveys of bottomfish in the main Hawaiian Islands, this study evaluates the effect of camera soak time on relative abundance metrics, fish length data, sampling efficiency, and power to detect differences in relative abundance and fish lengths. A soak time of 15min was found to be the shortest duration able to capture bottomfish abundance and length metrics while 30min generated data that did not significantly differ from the standard 40-min soak time. These shorter soak times allow for better survey efficiency and improved cost–benefit through increased levels of field sampling and reductions in video-processing time, while maintaining the power to detect differences in bottomfish relative abundance and lengths. The main drawback to shortening soak time was the concurrent reduction in the number of length measurements collected per species. An increased sample yield can alleviate this effect but only for bottomfish with a higher frequency of occurrence. Species-specific patterns in abundance were apparent in this study suggesting a strong influence of fish behavior on stereo-video abundance metrics. While a soak time of 15 to 30min was found to be sufficient for effectively sampling bottomfish, the cost–benefit of employing a given soak time in future stereo-video surveys should be assessed based on the target species and survey goals.

Isothermal crystallization and effect of soak time on phase evolution, microstructure and ionic conductivity of Li2O–Al2O3–TiO2–P2O5 glass–ceramic

Glass–ceramics derived from Li2O–Al2O3–TiO2–P2O5 vitreous system were obtained by isothermal heat treatment at 700°C, for different soak times ranging from 0 to 60h. Phase analysis revealed mixture of amorphous and crystalline phases for short soak times (<1h). By 1h of soak time, crystallization was complete and phases were ascribed to dominant Li1+xAlxTi2−x(PO4)3 (LATP) along with secondary AlPO4 and TiO2, previously reported. Microstructural evolution with soak time was imaged using high resolution scanning electron microscope (SEM). Crystalline volume fraction in glass–ceramics was estimated from image analysis and it followed Kolmogorov–Johnson–Mehl–Avrami (KJMA) equation. Conductivity of glass–ceramics was derived using impedance spectroscopy data for all soak times and correlated to the crystalline volume content. After attaining a critical volume of crystalline phase/s, conductivity increased significantly and was observed to follow the scaling equation σdc~(V−Vc)β, where σdc is dc conductivity, V is crystalline volume content, Vc is threshold value of crystalline volume content above which sudden increase in conductivity was observed and β is scaling exponent. Vc≈30% was in accordance with percolation scaling law and is attributed to formation of 3D conducting channel network in the glass–ceramics microstructure.

Effect of Soaking Time in Alkali Solution on the Interfacial Shear Strength of Cantala Fiber/Recycled HDPE Composites

The interfacial shear strength (IFSS) between natural fibers and thermoplastics matrix is one of the key parameters to increase the mechanical properties of composites. IFSS can be improved by alkali treatment. Therefore, the research is to investigate the influence of IFSS soaking time in alkali solution of cantala fiber/Recycled High Density Polyethylene (RHDPE) composites. Experimentally, cantala fiber/RHDPE composites were manufactured by simple hot press machine. Alkali treatment on the surface of cantala fibers was carried out on 2% sodium hydroxide (NaOH) solution for a period time, i.e., 0, 4, 8, 12, 16, 20, and 24 hours. The IFSS value of composites was observed using single fiber pullout test method. The result shows that the increase of soaking time in alkali solution could improve IFSS of cantala fiber/RHDPE composites by 43%.

ANALISIS SIFAT PENYERAPAN AIR DAN INDEKS NYALA API PADA PAPAN KOMPOSIT YANG DI PERKUAT SERAT DAUN PANDAN DURI DAN LIMBAH SERBUK GERGAJI KAYU SENGON DENGAN RESIN POLYESTER

The use of composite materials as an alternative to metallic materials in the field of engineering more widespread, not only as an interior daneksterior in the automotive field but also extended to other areas such as property and architecture is to reduce the incidence of fire one only to find a replacement for wood as a raw material of houses and buildings with other alternative materials are more fire resistant, the material need not be limited in mechanical strength, but also on the physical properties. Therefore, the aim of this study was to analyze the absorption properties of water and fire index in the fiber-reinforced composite board pandanus leaves thorns and wood sawdust filler sengon with polyester resin as matriknya.Analysis of the absorption properties of the water carried by the ASTM D 5529 with a variation of the length of time of immersion (10, 20, and 30 days) and the fiber volume fraction (0%, 10%, 20% and 30%). Testing index of the flame using ASTM E1321 with long burning time of 10 minutes. To test the effect of soaking time and a fiber volume fraction of the weight gain, volume, and density on the board fiber composite pandanus thorns with 10% filler wood sawdust sengon diguanakn Two Ways Analysis Of Variance, and the effect of fiber volume fraction to index Flash Fire is used One Ways Analysis Of Variance.The results showed that the water absorption is affected by fiber volume fraction and longer soaking time. The largest percentage of water absorption occurs in the volume fraction of 30% with long soaking time of 30 days is 24.41%. Similarly, the highest percentage swelling occurs in composite board with a volume fraction of 30% with a 30-day long soaking time is 11:22% .Then the flame to the percentage of the index without fiber composite board has a greater percentage is 167.03%. By contrast the percentage of board composite index gained shortest of composite board with a fiber volume fraction of 30% ie 70.25% composite board with a fiber volume fraction of 30% also have a flame index is lower than the comparison is with wood composites sengon.

Impact Behavior of Three Notched All-Ceramic Restorations after Soaking in Artificial Saliva.

Biomechanics play a critical role in influencing the clinical applications of all-ceramic dental restorations. The restorative biomaterials have to demonstrate mechanical durability in the oral environment because they are always exposed to a variety of oral environments. This study was designed to evaluate the effect of soaking time, notch and saliva pH values on the impact energy of three commonly used all-ceramic materials for CAD/CAM. The leucite-reinforced glass ceramic (ProCAD), lithium disilicate glass ceramic (IPS e.max CAD) and zirconia-based ceramic materials (IPS e.max ZirCAD) were used. The experimental results indicated that the impact energy of ProCAD decreased with an increase in soaking time, but not for IPS e.max CAD and IPS e.max ZirCAD. The impact energy of the zirconia system was higher than leucite-reinforced and lithium disilicate-based ceramic systems. When subjected to preformed 0.5 mm U-shape notch on the bar specimen of 3 mm thick, the impact energy of the all-ceramic restorations revealed a markedly reduction of about 80%–90%, almost irrespective of dental compositions, which indicated the effect of flaw to a great degree. No statistically significant influence (p > 0.05) of pH values (4, 7 and 9) on impact energy was found for each group. It is concluded that the no matter which all-ceramic materials were used, it was appreciably sensitive to the presence of notches. The ceramic composition and microstructure have been shown to affect mechanical durability.

Study of Aminosilane-Compound Modification Condition on Polished Silicon Wafer and Its Influence on the Adhesion of Electroless Nickel/Phosphorous Film

Electroless deposition (ELD) of nickel/phosphorous (Ni/P) layer has been a special interest in modern technique, especially in the production of diffusion barriers in the silicon industry [1]. The crucial part of ELD is a catalytic reaction that needs a trace amount of palladium [2] as the activator to lower the activation energy of metal formation. Due to the adhesion of ELD Ni/P film is associated with the interfacial property of catalyst and silicon surface. In order to increase the bridging between the silicon substrate and palladium catalyst, modifying silicon surface with organo-silane compound such as 3-[2-(2-aminoethylamino)ethylamino] propyl-trimethoxysilane (ETAS). The ETAS then form a self-assembled monolayer (SAM) to facilitate the adsorption of palladium catalyst [3]. However, it is known that the SAM formation is very sensitive to process condition such as soaking time, soaking temperature and solvent agents. In this study, the ETAS modification condition on silicon wafer is investigated. In particular, the ETAS-modified film was fabricated by a wet-soaking method and the effects of soaking time, soaking temperature and solvent agents onto silicon surface were discussed. As shown in Fig 1, the images of AFM with various soaking time of ETAS-modified silicon surface showed significant difference; this means that the long soaking time did influence SAM formation. Finally, the adhesion of ELD Ni/P on ETAS-modified silicon surface with different process parameters is discussed. REFERENCES [1] A. Brenner, G.E. Riddell, J. Res. Nat'l Bur. Std. 37 (1946) 31. [2] L. Li, B. Liu, Mater. Chem. Phys. 128 (2011) 303. [3] T. C. Wei, T. P. Pan, C. M. Chen, K. C. Lai, C. H. Wu, Electrochem. Commun. 54 (2015) 6 Figure 1

The Effect of Cryogenic Treatment on Microstructure and Mechanical Response of AISI D3 Tool Steel Punches

Recently, deep cryogenic treatment is performed to improve the mechanical responses (wear, hardness, fatigue, and thermal conductivity) of various steel components. Researchers have tried to evaluate the eco-friendly and nontoxic process to optimize the parameters. Cold-shearing punches used to manufacture various holes that undergo severe impact loading and wear in the metal forming process. This study concerns the effect of soaking time (24 hr, 36 hr) at liquid nitrogen temperature (−145 °C) during the deep cryogenic treatment on the microstructural changes which are carbide distribution and retained austenite percentage of AISI D3 tool steel punches. It was shown that the deep cryogenic treatment reduces retained austenite and enhanced uniform distribution of carbide particles. It is concluded that for significantly improved punch life and performance, it is an advisable application of 36 hr deep cryogenic treatment.

Wettability and interfacial characterization of alkaline treated kenaf fiber-unsaturated polyester composites fabricated by resin transfer molding

This paper reports on comprehensive characterization of wettability and interfacial properties of kenaf fibers (KF) and its unsaturated polyester (UPR) composites fabricated by resin transfer molding (RTM). KF were chemically modified by immersing in 6% NaOH concentration for 1, 2, 3, 4, and 5 h to enhance the interaction between KF and UPR. FTIR spectral data showed the chemical changes in KF after treatment which induced the modification of physical and wettability characteristics of KF. The changes in crystalinity index (CrI) and thermal stability of KF content were analyzed using X-ray diffraction (XRD) and thermogravimetry (TGA) techniques, respectively. Scanning electron microscope (SEM) shows a cleaner KF surface upon KF treatment and atomic force microscopy (AFM) signify an increasing in available fiber–matrix specific contact area. Wettability of KF was investigated by means of surface energy measurement using Washburn contact angle principle via Owens–Wendt–Rabel–Kaelble (OWRK) method. Surface energy was found to increase with longer soaking time. The effect of soaking time of alkaline treatment in enhancing the interface bonding characteristic between the KF and UPR matrices can be reflected by the ILSS value of the composites. The highest value of ILSS was recorded by 3 h treated KF composite. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

A novel multiple soaking temperature (MST) method to prepare polylactic acid foams with bi-modal open-pore structure and their potential in tissue engineering applications

Bi-modal pore structures were obtained by stepwise depressurization in batch foaming method. In this study, a novel method was developed to produce polylactic acid (PLA) foam with bi-modal pore structure by using multiple soaking temperature (MST) method based on one-step pressure release. The effects of soaking time and temperatures on the formation of bi-modal pore structure were investigated in detail. The formation of macro pores was attributed to the synergistic effect of the supercritical carbon dioxide (SC-CO2) aggregation and the depressurization process. Moreover, bi-modal open-pore structures could be obtained at certain processing conditions. The PLA foams achieved porosity and open pore content as high as 87.9% and 82.4%, with average macro and micro pore size of 150μm and 8μm, respectively. The biocompatibility of the PLA open-pore foams was verified by 3T3 fibroblast cell culture.