wear

摘要： Hybrid materials collected from organic and inorganic sources,which are traditionally used as brake lining materials,generally include fly ash,cashew shell powder,phenolic resins,aluminium wool,barites,lime powder,carbon powder and copper powder.The present research focuses on the specific effects produced by fly ash and aims to provide useful indications for the replacement of asbestos due to the health hazards caused by the related fibers.Furthermore,the financial implications related to the use of large-volume use of fly ash,lime stone and cashew shell powder,readily available in most countries in the world,are also discussed.It is shown that many manufacturing and automotive industries,which are currently experiencing difficulties in meeting the increasing demand for brake lining material,may take advantage from the proposed solution.

摘要： The fabrication of boron carbide reinforced aluminum matrix composites(Al-B_(4)C)with various contents of B_(4)C(1wt%,6wt%,15wt%,and 30wt%)was performed by powder metallurgy,and the influence of the content of B_(4)C on their mechanical and tribological behavior was examined.The Al-30B_(4)C composites recorded the highest density(~2.54 g/cm^(3)),lowest porosity(4%),maximum Vickers hardness(HV~75),lowest weight loss(0.4 mg),and lowest specific wear rate(0.00042 mm^(3)/(N·m))under a load of 7 N,with an enhancement of 167%in hardness,a decrease of 75.8%in weight loss,and a decrease of 76.7%in the specific wear rate compared with pure aluminum.In addition,the scanning electron microscope images of the worn surface revealed that the Al-B_(4)C composite has the narrowest wear groove of 0.85 mm at a load of 7 N,and the main wear mechanism was observed as an abrasive wear mechanism.According to the friction analysis,the coefficient of friction between surfaces increased with increasing boron carbide content and with decreasing applied load.In conclusion,B_(4)C is an effective reinforcement material in terms of tribological and mechanical performance of the Al-B_(4)C composites.

摘要： 专利名称:RESTORABLE ANNTENNAE APPARATUS AND SYSTEM FOR WELL LOGGING专利申请号:EP20180182195申请日:2014.03.11公开号:EP3404451(B1)公开日:2020.01.22申请人:China National Petroleum Corporation;Oliden Technology,LLC An apparatus includes a sub with recesses along an exterior wall to receive inserts,an antennae case including a coil surrounded by a sacrificial wear portion of a material through which signals between the coil and a formation of interest may pass.An eroded outer wall of the sacrificial wear portion is restorable by application of an uncured restorative material to the antennae case.A method includes securing an antennae case having a coil there within onto a sub,surrounding the coil with a metal sleeve shield,and radially receiving and securing a multi-piece sacrificial wear member intermediate the antennae case and a retainer ring having a threaded bore.The multi-piece sacrificial wear member is replaceable after use by unthreading the retainer ring to release the sacrificial wear member for radial removal from the sub.

摘要： This paper presents an experimental investigation of the mechanical and tribological properties of Cu-graphene nanosheets(GN)nanocomposites.We employed the electroless coating process to coat GNs with Ag particles to avoid its reaction with Cu and the formation of intermetallic phases.We analyzed the effect of GN content on the structural,mechanical,and tribological properties of the produced nanocom-posites.Results showed that the electroless coating process is an efficient technique to avoid the reaction between Cu and C and the formation of intermetallic phases.The addition of GNs significantly improves the mechanical and tribological properties of Cu nanocomposites.However,the addition of GNs needs to be done carefully because,after a certain threshold value,the mechanical and tribological properties are negatively affected.The optimum GN content is determined to be 0.5vol%,at which hardness,wear rate,and coefficient of friction are im-proved by 13%,81.9%,and 49.8%,respectively,compared with Cu nanocomposites.These improved properties are due to the reduced crys-tallite size,presence of GNs,and homogenous distribution of the composite constituents.

摘要： Aluminium hybrid functionally graded metal matrix composites(FGMMCs),meet growing demands for supreme tribo-mechanical performance in automotive and aviation industry.This research experimentally compares the influence of carbide ceramics(B_(4)C,SiC,TiC)as reinforcements,in improving reciprocating tribology performance and mechanical strength of A333 hybrid composites against alloy.Hollow cylindrical samples of A333/6 wt%B_(4)C/4 wt%TiC and A333/6 wt%B_(4)C/4 wt%SiC hybrid FGMMCs were developed using horizontal centrifugal casting.Metallography analysis on both composites revealed increasing ceramic gradient distribution towards outer composite wall.Particle rich zone of A333/B_(4)C/SiC hybrid FGMMC showed maximum micro-hardness(198.9 HV)and tensile strength(267.9 MPa).Elemental mapping confirmed effective distribution of ceramics and detected elemental composition of both composites.Particle rich layer of A333/B_(4)C/SiC hybrid FGMMC exhibited improved wear resistance in comparison with all three layers of A333/B_(4)C/TiC hybrid FGMMC and alloy.Third-body abrasion and tribo-chemical wear were the predominant mechanisms revealed for both composites during worn surface analysis.

摘要： 专利名称:RESTORABLE ANNTENNAE APPARATUS AND SYSTEM FOR WELL LOGGING专利申请号:EP20180182195申请日:2014.03.11公开号:EP3404451(B1)公开日:2020.01.22申请人:China National Petroleum Corporation;Oliden Technology,LLC An apparatus includes a sub with recesses along an exterior wall to receive inserts,an antennae case including a coil surrounded by a sacrificial wear portion of a material through which signals between the coil and a formation of interest may pass.An eroded outer wall of the sacrificial wear portion is restorable by application of an uncured restorative material to the antennae case.A method includes securing an antennae case having a coil there within onto a sub,surrounding the coil with a metal sleeve shield,and radially receiving and securing a multi-piece sacrificial wear member intermediate the antennae case and a retainer ring having a threaded bore.The multi-piece sacrificial wear member is replaceable after use by unthreading the retainer ring to release the sacrificial wear member for radial removal from the sub.

摘要： BACKGROUND Individuals with heart failure(HF)frequently experience limitations in mobility,but specific aspects of these limitations are not well understood.This study investigated the association of HF severity,based on the New York Heart Associ-ation(NYHA)classes,with digital mobility outcomes(DMOs)and handgrip strength in older inpatients with HF.METHODS For this explorative analysis,hospital admission and discharge data from an ongoing,prospective cohort study were used.The sample included older participants with HF and a sub-sample of heart-healthy individuals.Participants were equipped with a wearable inertial measurement unit(IMU)system during mobility performance(balancing,sit-to-stand transfer,walking).We analyzed the association between 17 DMOs and HF severity with multiple linear regression models.RESULTS The total sample included 61 older participants(65-97 years of age,55.7%female).Of all DMOs,only sway path in a semi-tandem stance position(m/s²)showed a relevant association with NYHA classes(admission:β=−0.28,P=0.09;discharge:β=−0.39,P=0.02).Handgrip strength showed a trend towards a significant association(admission:β=−0.15,P=0.10;discharge:β=−0.15,P=0.19).CONCLUSIONS This is to our best knowledge the first analysis on the association of HF severity and IMU-based DMOs.Sway path and handgrip strength may be the most promising parameters for monitoring mobility aspects in treatment of HF.

摘要： Drowning is a serious risk to children.If the child is wearing a smart anti-drowning device,the device can automatically detect if the wearer is in danger of drowning and send an alert to the guardian's mobile phone.In daily life and sports,the application of wearable electronic devices in underwater can effectively detect or analyze the underwater activity characteristics of wearers.

摘要： The development of numerical models able to compute the wheel and rail profile wear is essential to improve the scheduling of maintenance operations required to restore the original profile shapes.This work surveys the main numerical models in the literature for the evaluation of the uniform wear of wheel and rail profiles.The standard structure of these tools includes a multibody simulation of the wheel-track coupled dynamics and a wear module implementing an experimental wear law.Therefore,the models are classified according to the strategy adopted for the worn profile update,ranging from models performing a single computation to models based on an online communication between the dynamic and wear modules.Nevertheless,the most common strategy nowadays relies on an iteration of dynamic simulations in which the profiles are left unchanged,with co-simulation techniques often adopted to increase the computational performances.Work is still needed to improve the accuracy of the current models.New experimental campaigns should be carried out to obtain refined wear coefficients and models,while strategies for the evaluation of both longitudinal and transversal wear,also considering the effects of tread braking,should be implemented to obtain accurate damage models.

摘要： In 2021,Manas et al.1 used data from the Toledo Study for Healthy Aging and reported that high accelerometer-derived step volume and(what they labeled)intensity were significantly associated with lower hospitalization(average followup=3.1 years)and all-cause mortality(average followup=5.7 years)in 768 older adults(average age=78.8±4.9 years,mean±SD).Step volume(expressed as steps/day)was averaged across all compliant days(i.e.,those with8 h/day of valid wear time).For their purposes,the authors defined intensity as the total step volume divided by the total valid minutes of accelerometer wear time.