Two material removal modes in chemical mechanical polishing:mechanical plowing vs.chemical bonding

With the rapid development of semiconductors,the number of materials needed to be polished sharply increases.The material properties vary significantly,posing challenges to chemical mechanical polishing(CMP).Accordingly,the study aimed to classify the material removal mechanism.Based on the CMP and atomic force microscopy results,the six representative metals can be preliminarily classified into two groups,presumably due to different material removal modes.From the tribology perspective,the first group of Cu,Co,and Ni may mainly rely on the mechanical plowing effect.After adding H_(2)O_(2),corrosion can be first enhanced and then suppressed,affecting the surface mechanical strength.Consequently,the material removal rate(MRR)and the surface roughness increase and decrease.By comparison,the second group of Ta,Ru,and Ti may primarily depend on the chemical bonding effect.Adding H_(2)O_(2)can promote oxidation,increasing interfacial chemical bonds.Therefore,the MRR increases,and the surface roughness decreases and levels off.In addition,CMP can be regulated by tuning the synergistic effect of oxidation,complexation,and dissolution for mechanical plowing,while tuning the synergistic effect of oxidation and ionic strength for chemical bonding.The findings provide mechanistic insight into the material removal mechanism in CMP.

Multiscale study of the dynamic friction coefficient due to asperity plowing

A macroscopically nominal flat surface is rough at the nanoscale level and consists of nanoasperities.Therefore,the frictional properties of the macroscale-level rough surface are determined by the mechanical behaviors of nanoasperity contact pairs under shear.In this work,we first used molecular dynamics simulations to study the non-adhesive shear between single contact pairs.Subsequently,to estimate the friction coefficient of rough surfaces,we implemented the frictional behavior of a single contact pair into a Greenwood-Williamson-type statistical model.By employing the present multiscale approach,we used the size,rate,and orientation effects,which originated from nanoscale dislocation plasticity,to determine the dependence of the macroscale friction coefficient on system parameters,such as the surface roughness,separation,loading velocity,and direction.Our model predicts an unconventional dependence of the friction coefficient on the normal contact load,which has been observed in nanoscale frictional tests.Therefore,this model represents one step toward understanding some of the relevant macroscopic phenomena of surface friction at the nanoscale level.

Effects of autumn plowing on the movement and correlation of moisture,heat and nitrate nitrogen in seasonal freeze-thaw soil

A two-year experiment was established in northern Xinjiang to investigate the effects of autumn plowing methods on nitrate nitrogen accumulation,spring-sown soil conditions and cotton emergence rate,and to explore the response relationship between soil water,heat and nitrate nitrogen.The experiment included five autumn plowing treatments,namely,plough tillage(FG),no-tillage(MG),ridge and furrow alternation(LG),plough tillage with straw mulch(FJ)and plough tillage with activated charcoal mulch(FH).The results showed that both FH and FJ treatments were beneficial to promote the nitrate-nitrogen accumulation in topsoil,while FG,MG and LG treatments aggravated the nitrate nitrogen leaching in topsoil.During the freezing period,FH and FJ treatments were beneficial to reduce soil heat loss and facilitate the coordinated upward migration of soil water and nitrate nitrogen.In the thawing period,FH and FJ treatments favored suppressing the synergistic downward transport of soil water and nitrate-nitrogen and motivated the synergistic upward migration of heat and nitrate nitrogen in deep soil.Binary regression analysis suggested that the interaction between water,heat and nitrate nitrogen under FH and FJ treatments showed a highly significant correlation.FH and FJ treatments showed obvious advantages in regulating soil conditions and optimizing soil water,heat and nitrate nitrogen co-transport mechanism.During the spring sowing period,the FH and FJ treatments increased the average soil temperature by 0.99℃and 1.29℃,and the average soil moisture content by 6.01%and 8.70%,and the average soil nitrate content by 10.20 mg/kg and 10.47 mg/kg,in the 0-25 cm soil layer,respectively.FH and FJ treatments significantly grew the emergence rate of cotton,which can be used as the main autumn tillage strategies in arid areas of northern Xinjiang.

Experimental Study on Water Saving of Large-scale Mechanized Paddy Field Production Process in Heilongjiang Province

In order to clarify the water-saving technologies and standards in large-scale mechanized production of paddy fields, the water-saving effects and cost-benefit situations of paddy field steeping, seedling transplanting and different land preparation methods were studied. The results showed that the suitable water layer height for the closing period of mechanized operation was 10 cm, which could save water, facilitate weed control, and lead to better effect and the highest yield. The treatment with a water layer height of 1 cm(Huadashui) for the seedling planting operation achieved better quality of seedling transplanting, lower vacancy rate and higher yield and was water-saving. From the perspective of saving water and taking into account the cost of land preparation, the method of steeping and beating the field was better than the method of plowing in autumn and rotary tillage and harrowing in spring, but it was very prone to lodging. From the perspective of high yield creation, the method of plowing in autumn and rotary tillage and harrowing in spring was significantly better than the method of steeping and beating the field. In order to reduce the cost of land preparation, it is recommended to change the way of plowing in autumn and rotary tillage and hallowing in spring to plowing in autumn and rotary tillage in spring or plowing and hallowing in spring to reduce the cost of one time of rotary tillage, and to simultaneously realize deeper plough layer, which is conducive to preventing lodging and obtaining high yield.

Design Principles of the Non-smooth Surface of Bionic Plow Moldboard

The diverse non-smooth body surfaces to reduce soil adhesion are the evolutional results for the soil animals to fit the adhesive and wet environment and can be used as a biological basis for the design of bionic plow moldboard. The model surfaces for bionic simulation should be taken from soil animal digging organs, on which the soil motion is similar to what is on the surface of moldboard. By analyzing the distribution of non-smooth units on the body surface of the ground beetle jaw and the soil moving stresses, the design principles of the bionic moldboard for the local and the whole moldboard were presented respectively. As well, the effect of soil moving speed on reducing adhesion, the dimensions relationship between soil particles and non-smooth convexes, the relationship between the enveloping surface of non-smooth convexes and the initial smooth surface of the plow body, and the convex types of the sphere coronal and the pangolin scales,etc.were discussed.

Evaluation of plow system performance in long-wall mining method using particle flow code

The underground or open-pit methods are used for the extraction of mineral resources,each of which is divided into different categories.Coal is one of the mineral resources,which is exploited either by the surface or the underground methods.The long-wall mining is one of the methods for the underground coal mining.In this method,which is a mechanized one,some machines such as the shearer or plow are used for the mining.The coal mine in Parvadeh,Tabas is a mechanized mine that is extracted by the long-wall mining.The modeling with particle flow code software was used in this mine for the evaluation of plow performance using the coal specifications.In this regard,the sample was first calibrated by sampling from the Parvadeh coal mine and performing the uniaxial and Brazilian tests on the model.Then,the modeling was done by constructing the model and using the variables such as the clearance angle and the linear velocity of the plow.After making 28 models for the plow,the best model of the plow was selected based on the maximum force applied to the machine in the X direction.Finally,the results of this study showed that the best plow performance is for a model with the clearance angle of zero and the linear velocity of 9 mm/min,and the maximum force applied to this model is equal to 39,000 kN in the X direction.

Plowshares Wear Investigation of the Plows Working in Mountainous Conditions Using Statistical Probabilistic Modeling

A general technique for modeling of the wear of machine parts using the theory of probability and mathematical statistics is developed,which is implemented through the example of plows of agricultural plows.Regularities of their wear during working under mountainous conditions are established,an adequate probabilistic-statistic mathematical model is obtained,general characteristics of the distribution of wear are determined using statistical moments and their most common(modal)values are determined which allow to substantiate the method of restoring worn parts for the purpose of increasing their life.This technique can also be utilized to study the regularity of wear of parts of other machines.

Application of Symmetric Ploughs for Tillage on Wetland Paddy Fields

Impertinent uses of moldboard plows for tillage on wetland paddy soils,as far more than a century,caused damage to its important hardpan layer of 20-30 cm soil depth that led to some extent,the decrease of rice production than it should have been.The current study has been carried out to repair that damage to regain the“lost”of paddy yields by using the designed flat-symmetric plow that has a lift angle of 29°-30°.It is towed by a hand tractor of 12 horsepower(HP)at a travel speed of 1.11 m/s and a working depth of 10 cm in three blocks of a wetland paddy field in Bandung Sub-district of West-Java,Indonesia.Test results observed from the formed plow sole of 10-15 cm depth underneath after 3rd-time operations of the plow on the same track,indicated that there was a relatively small decrease of moisture content(MC)around 0.182%,as well as increases of cone index(CI)and bulk density(BD)around 0.172%and 0.171%,respectively.This plow was able to maintain,generate and stimulate the formation of hardpan right underneath the plow path.It was due to the improvement of hardpan physical-mechanical properties and would be more significant after frequent tillage using that plow.Hence,there is a chance to develop a tillage method in the development of an ideal wetland paddy cultivation system throughout Indonesian wetland paddy fields.

Mechanical, tribological and anti-corrosive properties of polyaniline/graphene coated Mg-9Li-7Al-1Sn and Mg-9Li-5Al-3Sn-1Zn alloys

The mechanical,tribological and corrosion protection offered to Mg-9Li-7Al-1Sn and Mg-9Li-5Al-3Sn-1Zn alloys by the epoxy coating containing polyaniline/graphene(PANI/Gr)pigments is undertaken in the current work.PANI/Gr containing coatings were observed to be strongly adherent with a higher scratch hardness(Hs)and plowing hardness(Hp),i.e.Hsof 0.43 GPa,and Hpof 0.61 GPa,respectively when compared to that of neat epoxy coating(Hsof 0.17 GPa,and Hpof 0.40 GPa,respectively).Due to their higher Hsand Hpvalues,PANI/Gr based coatings displayed an enhanced wear resistance(Wear volume,Wv=4.53×10^-3 m^3)than that of neat epoxy coating(Wv=5.15×10^-3 m^3).The corrosion protection efficiency in corrosive environment of 3.5 wt%NaCl solution was obtained to be>99% for PANI/Gr containing coatings when compared to that of neat epoxy coating.The charge-transfer resistance(R(ct))of the PANI/Gr containing coatings were estimated to be>10^6 cm^2,which indicates their highly protective nature when compared to that of neat epoxy coating(R(ct)10^5 Ω cm^2).Hence,PANI/Gr containing coatings can be potentially used for wear resistance and corrosion protection applications in marine environments.

Feasibility of implementation of intelligent simulation configurations based on data mining methodologies for prediction of tractor wheel slip

This paper deals with implementation of intelligent simulation configurations for prediction of tractor wheel slip in tillage operations.The effects of numeral variables of forward speed(2,4,and 6 km/h)and plowing depth(10,20,and 30 cm),and nominal variable of tractor driving mode(two-wheel drive(2WD)and four-wheel drive(4WD))on tractor rear wheel slip were intelligently simulated utilizing data mining methodologies of artificial neural network(ANN)and adaptive neuro-fuzzy inference system(ANFIS).Neuro-fuzzy potential of the ANFIS simulation framework against neural ability of the ANN simulation framework was apprised.Results confirmed higher efficiency of the best configuration of the ANFIS simulation framework with satisfactory statistical performance criteria of coefficient of determination(0.981),root mean square error(1.124%),mean absolute percentage error(1.515%),and mean of absolute values of prediction residual errors(1.135%)than that of the ANN simulation framework.Physical perception obtained from the ANFIS simulation results demonstrated that the wheel slip increased nonlinearly with increment of forward speed and plowing depth,while it decreased as tractor driving mode changed from the 2WD to 4WD.Therefore,the best configuration of the ANFIS based intelligent simulation framework implemented in this study can be used for further relevant studies of tractor rear wheel slip as a reference.

Application of adaptive neuro-fuzzy inference system to predict draft and energy requirements of a disk plow

The energy and draft requirements of a disk plow have been recognized as essential factors when attempting to correctly match it with tractor power.This study examines the possible of using an adaptive neuro-fuzzy inference system(ANFIS)approach and its performance compared to a multiple linear regression(MLR)model to determine the energy and draft requirements of a disk plow.A total of 133 data patterns were obtained by conducting experiments in the field and from the literature.Of these 133 data points,121 were arbitrarily selected and used for training,and the remaining 12 were used for testing the models.The input variables were plowing depth,plowing speed,soil texture index,initial soil moisture content,initial soil bulk density,disk diameter,disk angle,and disk tilt angle,and output variable was draft of the disk plow.Four membership functions were used with ANFIS:a triangular membership function,generalized bell-shaped membership function,trapezoidal membership function,and Gaussian curve membership function.An evaluation of the outcomes of the ANFIS and MLR modeling shows that the triangular membership function performed better than the other functions.When the ANFIS model draft predictions were compared to the measured values,the average relative error was-1.97%.A comparison of the ANFIS model with other approaches showed that the energy and draft requirements of the disk plow could be estimated with satisfactory accuracy.